Clayton is set to feature against his former club Leeds for Boro at the Riverside Stadium in the Championship tomorrow afternoon.
The 26-year-old initially joined the West Yorkshire outfit on a loan deal from Manchester City in 2010 before signing for the Whites on a permanent contract.
The Englishman left Leeds in the summer of 2012 for Huddersfield Town and moved to Boro two years ago.
Clayton has stated that he enjoyed his time at the Whites, and that he has fond memories of Leeds.
“I had a good time there (Leeds),” the former Manchester City prospect told Middlesbrough’s official website.
“It was really the start of my career at this level and I’ll always have a fondness for the club as a whole.”
Middlesbrough will head into Sunday’s match on the back of a 3-0 victory over Wolverhampton Wanderers at the Riverside Stadium in the third round of the League Cup.
Meanwhile, Leeds will head into the match on the back of a 2-1 victory over Milton Keynes Dones away from home in the Championship.