Blues salvaged a point from their opening game of the Championship season at St Andrews when Nikola Zigic's 93 minute goal cancelled out Leon Cort's 81st minute goal for the newly promoted south-London side.
"It was not our most fluent performance," Clark said after the game. "Some of our players were not exploding.
"These things happen in the early part of the season.
"It is credit to them that they showed great character to come back from what you were thinking was going to be a defeat when you are in injury time and a goal down to snatch a point.
"It is sign of a good time to come back as they did when our general performance has not been great."