The 25-year-old defender is being eased back following an eight-month injury nightmare. Leacock's campaign was decimated last season by groin and pelvic problems. His last first-team appearance came in a Carling Cup victory at Brighton on November 4.
The centre-half reported back for pre-season training with the rest of the squad and played 45 minutes of last weekend's friendly at Burton.
Clough told the Derby Telegraph: "Dean has done everything in training so far and it was lovely to see him back on the pitch because that was a big step for him.
"We were not sure if he was going to last 45 minutes. We had him pencilled in for 30 minutes at Burton, but he said he was okay. Him getting through it was as big a plus as we had on the day.
"The plan is to be as careful as we can with him and we are not going to rush him. It is more important that he gets right and fully fit."