Clancy stressed he was left with no option given the treacherous conditions in Maryhill, where the game was goalless when it was called off.
Heavy rain had left the Firhill pitch in a state that Clancy felt was dangerous, and the referee said: "The ultimate factor for us was player safety.
"It's of paramount importance when you're having to take a decision on the condition of the park.
"We felt, certainly as we were approaching half-time, that there were parts of the park, one corner in particular, where the ball wasn't rolling properly.
"It was sticking when it was coming out of the air and some players were even over-running the ball and it was ending up behind them, so it has the potential for ruining the match, but also causing an injury to a player if it was misjudged.
"We felt before the match that the pitch was playable, I had a word with both managers to discuss the conditions on the park, but as we were approaching half-time with the relentless rain, areas of the park were getting worse and indeed, some of the players were expressing reservations and concerns from both teams.
"Parts of the park had simply become unplayable."
St Johnstone manager Wright put his own disappointment at the game being abandoned with his men dominating play to one side, as he also felt the referee had made the correct decision.
"We had it explained to us before the game that he thought the pitch was playable, and I think it was, but as the half went on, particularly the far side got worse," said Wright.
"He (Clancy) said he would assess it as the game went on, that's what he's done and he's made the correct decision.
"I thought we were the better team. I thought we adapted to conditions better, so from that point of view we're disappointed the game didn't continue, but listen, the referee's got a lot of responsibility for players' safety and I would never question a decision where he puts player safety at the top of the list."