Chap's dead leg (3)
I believe the answer is:
don
'chap's' is the definition.
'dead leg' is the wordplay.
'dead' becomes 'd'.
'leg' becomes 'on' (cricket term, fielding positions).
'd'+'on'='DON'
(Other definitions for don that I've seen before include "Yorkshire river" , "Bradman, the ---" , "Get into" , "Put on; man's name" , "- - Giovanni, 26" .)