The Blades are seeking a replacement for Paul Coutts after he was ruled out of the season after breaking his leg in mid November and manager Chris Wilder has made a new central midfield enforcer a priority for the January window.
Former Leeds United and Huddersfield Town midfielder Clayton has made just one appearance since mid-October after falling out of favour under former manager Garry Monk, with Blades chiefs having reportedly enquired about his availability.
It remains to be seen if Clayton is part of the plans of new manager Tony Pulis and, if he is not, a move elsewhere is likely to be sanctioned.
Peterborough United director of football Barry Fry has confirmed that the club have received bids for star duo Jack Marriott and Marcus Maddison.
Marriott and Maddison are being watched by a host of Championship clubs, with Leeds United said to be one.
Fry said: “We’ve had £2m bids from Championship clubs, but that isn’t enough for us to even start talking, We don’t want to lose either of them.
“Maddison has nine goals and 23 assists this season which pretty much makes him irreplaceable.”
Scunthorpe United manager Graham Alexander has clarified the situation with in-demand £1m-rated winger Hakeeb Adelukan, subject of interest from a number of clubs, including Hull City and Barnsley.
On Adelukan, out of contract in the summer, Alexander confirmed: “We have had no bids for Hakeeb.
“I expect interest in a number of our players because we have got some real good young talent playing week in week out and winning games at a good level.
“I doubt it will be the last of the speculation about one of our players but we want to keep this good team together.
“But we understand the nature of the business and the food chain. We are not at the top of it – we are not Manchester City – and everyone has their price.”