Benteke has been in outstanding form since his £7 million summer move from Gent and is Villa's current top scorer with nine goals.
But he was guilty of failing to convert several gilt-edged opportunities in the last two matches against Bradford and Southampton which both ended in defeat.
Clark said: "It was just one of those days against Southampton. It wasn't just Christian. We are not putting chances away as a team. We need to defend as a team and attack as a team.
"On another day, we could have scored three or four goals and then it's a different game. The luck is not with us and hopefully that will change.
"Christian has been brilliant for us this season. It's a team performance and we are all disappointed with each other that we haven't taken our chances
"The good thing is we have created lots of chances. It would be different if we were losing games and weren't creating at all and were worried about how we are going to score.
"But we're causing teams problems. We just have to stick together and the luck will turn for us."