Withdraw with a slight injury (7)
I believe the answer is:
scratch
I believe this clue is a double definition.
'withdraw' is the first definition.
(I know that scratch is a more specific form of the action cancel)
'slight injury' is the second definition.
(I've seen this before)
'with a' is the link.
(Other definitions for scratch that I've seen before include "Handicap where expected to make" , "slight injury" , "score with > no handicap given" , "Deal with itch - cancel entry" , "Score - postpone indefinitely" .)