Left bill over dish (3)
I believe the answer is:
dal
'dish' is the definition.
(I've seen this before)
'left bill over' is the wordplay.
'left' becomes 'l' (common abbreviation).
'bill' becomes 'ad' (advertisement stuck on wall).
'over' says the letters should be written backwards.
'l'+'ad'='lad'
'lad' in reverse letter order is 'DAL'.
(Other definitions for dal that I've seen before include "Pigeon pea" , "Indian pulse puree" , "Indian dish of pulses" .)