The loanee centre-half missed last week's home defeat against Bournemouth as he recovered from a bout of tonsillitis.
Although he is inexperienced, Clark feels the England U21 international can help Blues tighten up defensively.
"Tom Thorpe is available," said the Blues boss. "He has had a good week’s training and looked extremely good.
"I've got no qualms about throwing him straight in. I saw enough in his first spell here and in his short time on the pitch against Derby to tell there is a good player there.
"We’ve got to rectify the defensive situation in terms of the goals that are going in. From front to back we haven’t defended well enough since the turn of the year. We’ve conceded 32 goals in 17 league and cup games, which is too many.
"We’re scoring enough but if you score two goals at home and you still lose, it can’t be right. That tells you where we have to sort things out."
Clark continued: "We lost two important players when we lost (Kyle) Bartley and (Dan) Burn.
“They were magnificent for us in the first half of the season and it was no coincidence that they played together in the ten game unbeaten run when we took 20 points from 30 and were just seven points from the play-offs."