Bank charge discount partially returned (4)
I believe the answer is:
side
'bank' is the definition.
('side' can be a synonym of 'bank')
'charge discount partially returned' is the wordplay.
'partially' indicates the answer is hidden within the clue.
'returned' is a reversal indicator.
'edis' is hidden within 'charge discount'.
'edis' written backwards gives 'SIDE'.
(Other definitions for side that I've seen before include "Not the main" , "superciliousness" , "Spin given to a ball by striking it off-centre" , "Football team" , "Left or right, say" .)