The centre-half has missed Blues' last two games with an ankle problem, but he returned to full training this week.
"Touch wood, Curtis will be ok for Derby," said the Blues boss. "We're hoping there is no reaction and he will be up for selection.
"I have also got Paul Caddis (shoulder) joining the group on Friday, but Saturday is too early for him. Certainly the games next week - depending on how his fitness levels are - could be a possibility though.
"So that's a brilliant bit of news because he was absolutely terrific in the three games he played for us and he had become a big favourite with the fans."
Meanwhile Clark says he is keeping his fingers crossed as to the extent of David Murphy's knee injury. The full-back undergoes exploratory surgery this evening.
"The big one is David, we're hoping it's the least worst scenario in terms of timescale and what the surgeon finds when he opens up the knee," added Clark.
"I'll have everything crossed when he is in surgery and hoping that we get the best result possible.
"That would probably be a minimum of four to six weeks, but the worst case scenario is what's called a micro-fracture of the knee and that would rule him out for five months."