Defender returned (4)
I believe the answer is:
back
I believe this clue is a double definition.
'defender' is the first definition.
(left-backs and right-backs are football defenders)
'returned' is the second definition.
(I've seen this before)
(Other definitions for back that I've seen before include "Give support to; player" , "Rear; spine" , "Help!" , "Series of popular time-travel movies" , "defensive player" .)