Zoltan Gera is out for the season after suffering a second serious ligament setback in just over 12 months but Clarke believes Thomas can profit from the Hungarian's misfortune.
Clarke said: "Jerome is the one that can cover for Zoltan because we didn't have Jerome in the first half of the season.
"He was always injured. Then when he got himself fit and was in the squad, the team was in a great place and he had no prospect of playing matches.
"He went out to Leeds to get match fitness, which he did, and he's come back to us and the timing couldn't be better."
"It's a great chance for him. He'll get chances to play.
"He'll be in and around the squad and the team and, what he has to do, is show the form he's shown in previous seasons because he's been a good servant for Albion.
"We look forward to some really good performances from him in the second half of the season.
"I think the month of December was a little bit up and down. We had good and bad spells.
"I think it is important we try and get back to a similar rhythm to what we had earlier in the season. I think we've lost that. We are not quite as fluent as we were."