The Belgian was furious when his side were denied a penalty just before half-time in the 2-1 loss despite right back Johnston clearly knocking the ball out of play in his own area using his arm following a tussle with Abdallah Sima.
Television footage later showed that Sima had been in an offside position when John Lundstram had played the ball to him – but Walsh awarded a goal kick following a VAR check by Collum at Clydesdale House.
Clement, whose team was trailing 1-0 at the time after allowing Paulo Bernardo to open the scoring, was unhappy with the ruling and questioned why the match official did not indicate the penalty had been disallowed for offside.
“I’m really disappointed we didn’t get a penalty in the first half,” he said. “It would have been a different story to go into the dressing-room at 1-1.
“My biggest frustration isn’t missing chances because (Erling) Haaland and (Kylian) Mbappe miss chances. My biggest frustration is that if there’s a clear handball, I don’t understand why it’s not a penalty given. It’s a clear thing so I’m curious about it.
“There was no communication towards me. I’m not a referee, but if the communication is that Sima is offside then there should have been a clear signal from VAR for offside. Then everyone knows the decision. There was no communication at that moment.
Clement, whose 16 game unbeaten run as manager came to an end with the Celtic loss, was bemused that he was booked in the first half for protesting about a throw-in which the hosts were given.
The Rangers manager, who agreed that his centre half Leon Balogun deserved to be shown a straight red card for a foul on Daizen Maeda with 19 minutes remaining, was also far from impressed that several of the hosts’ players did not receive second yellows for bad challenges.
READ MORE: Celtic 2 Rangers 1: Instant reaction to the burning issues
“I asked the referee at full-time why I got a yellow card,” he said. “He said I reacted too hard about a ball that was clearly ours but was given to the other side. It was a small reaction, no swearing, nothing. But it was a day like that for us.
“I didn’t see the images (of the Balogun foul on Maeda), but I think it’s a red card. If he was the last man, it was a red card, so nothing to discuss about that. But maybe we need to discuss then why there was no second yellow for a few tackles from players who had yellows on the other side.
“But I don’t want to go much into that. I’m not going to go into details about every action. I think you guys like to go deep into every detail about everything and every word I say, or other coaches and the players. So, it’s interesting to see the evaluation of everybody about those circumstances.
“That’s finished. I’m disappointed we don’t have three points, or even one point, because for me my team really deserved it today. We are going to work hard to get a lot of points in the next couple of months.
“I’m focused on my team, I want to make them better. The circumstances were not on our side, that’s clear, and we fought until the last second to get the game over the line. We were almost there, even with 10, so there are things to build on.”
READ MORE: Rangers captain laments ‘questionable’ calls and poor finishing
Clement, whose team is now eight points behind their city rivals in the league table with two games in hand, sportingly described the Kyogo Furuhashi strike which clinched the victory for Celtic as “world class”.
However, the former Genk, Club Brugge and Monaco manager stressed that he was proud of how Rangers, who pulled a goal back when James Tavernier netted a free-kick with two minutes of regulation time remaining, acquitted themselves.
“They were more efficient on the day and when games are in the balance like that, you can lose them. It could have been a draw, we could have won it. But the circumstances weren’t on our side.
“My team reacted in the second half, even after a world class goal to make it 2-0. It’s a very good goal and you can’t do too many things about it. But we never stopped, even with 10 men. We kept going and created enough chances to score our goal and others. We went until the end and everyone here became nervous.
“So I see a team that’s growing with more resilience, mentality and quality on the ball. If the circumstances go against you, you can lose these games. It’s not an opportunity lost for us. That’s when you don’t show enough quality or do enough things to win points.”
Asked about the implications of the result on the Scottish title race, he said. “I’m not busy talking about that. I told you guys that we are busy with the marathon, I’m busy with making the team better, I’m busy with myself. I’m not busy with other teams and how they are performing.
“So, I see a team, what they did today they could not have done that two months ago, or even four or five weeks ago. We are going to keep on building and make it better and better.”
GET MORE NEWS HERE