After a bright start to his Baggies career, Sessegnon's form has dropped off in recent weeks and he has found himself relegated to the bench.
But Clarke is fully behind his £6million capture from Sunderland and says he will soon be back on the goal-scoring trail.
"He doesn't say much but he is confident enough. Every attacking player misses chances," Clarke told the Birmingham Mail.
"Stephane knows that and he will keep getting in the right positions and he will score goals for us and he will be good for us.
"I don't think he is lacking confidence.
"He tried hard for us at Newcastle. It was a difficult game for him to get into. He couldn't really get into it to affect it too much for us.
"But that is different to confidence. He is confident enough. We just couldn't get him in the game enough."