Fighting back, dish out unfair treatment (3,4)
I believe the answer is:
raw deal
'unfair treatment' is the definition.
(I've seen this before)
'fighting back dish out' is the wordplay.
'fighting' becomes 'war'.
'back' is a reversal indicator.
'dish out' becomes 'deal' (dealing is a kind of dishing out).
'war' backwards is 'raw'.
'raw'+'deal'='RAW DEAL'
(Other definitions for raw deal that I've seen before include "Unfair treatment like uncooked timber" , "Untreated wood" , "'Harsh, unfair treatment (3,4)'" , "Unjust arrangement" , "Unfair arrangement" .)