The Rams boss expressed his delight at having the Republic of Ireland youth international back from injury, describing him as a 'great' defensive option
The 19-year-old defender returned to action in Derby's pre-season game against Burton and Clough expressed his delight at seeing the player back in action.
"It was brilliant to see Mark get back on the pitch, " Clough told the club's official website. "He's had a tough few months but he's worked incredibly hard and to see him out there again was tremendous."
He added:"He's used his time out wisely to bulk up as well and he's looking very strong now. But his attitude has been spot on and he's back on schedule which is pleasing for him and us."
The Dublin born defender has had several injury scares in recent years, undergoing heart surgery in 2009 and he had been a regular in the Rams defence in the 2011/2012 season before a cruciate ligament injury ruled him out.
"He's competitive and a natural defender, so it's great to have him back as a defensive option this season," Clough continued. "Last season Mark surpassed expectations in many ways, so it'll be interesting to see how he does this season.
"We've got good competition in the central defensive area of the team now, and Mark coming back into the fold is certainly a big boost," concluded the Derby boss.