Clapham, a former Ipswich team-mate of interim manager Mark Venus, will assist he and first-team coach Mark Proctor, with youth-team coach Graeme Lee moving up to Under-21 level for the time being.
Venus told the club's official website: "I feel we needed another set of hands.
"I know Jamie. He's still learning a little bit but he will help me. Proc has guided him a little bit as well and I'm pretty comfortable that the training ground is as efficient as we want it to be.
"I think it's good for the football club that the coaches sometimes go into different areas, coach different players and take different responsibilities."