The 21-year-old initially arrived at Elland Road on loan at the start of the month and has made two substitute appearances, against Derby and Nottingham Forest.
Clayton, who progressed through City's academy, spent most of last season on loan at Carlisle, where he made a total of 28 appearances.
Clayton failed to make the first-team breakthrough at Eastlands, but was twice an unused substitute.
Source: PA
Source: PA