Speaking on the official Leeds website, Clapham said: "I had a phone call from Mick McCarthy on Friday telling me that Leeds had been in contact.
"Unfortunately I couldn't get up here in time on the Friday, but I trained with some of the lads on Saturday morning and went to the game in the afternoon."
The 31-year old full-back is now contracted until September 30.
The former Spurs, Ipswich and Birmingham left-back claimed the 15-point deduction Leeds incurred was not an off-putting factor in his move.
"I'm here to play football for the next five weeks and I'm looking forward to it," he added.
"At the moment it's 15 points off the top, and hopefully by the end of September we'll be in the positives points-wise."