Back listener supporting right (4)
I believe the answer is:
rear
'back' is the definition.
(something's rear is its back)
'listener supporting right' is the wordplay.
'listener' becomes 'ear' (body part which hears or listens).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'right' becomes 'r' (abbreviation).
'ear' put after 'r' is 'REAR'.
(Other definitions for rear that I've seen before include "Posterior" , "Buck" , "Jump" , "Foster" , "Bring up - the tail" .)