Partial refund (6)
I believe the answer is:
rebate
'partial refund' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for rebate that I've seen before include "Partial refund, reduction in payment" , "(Eg, tax) refund" , "Refund - discount" , "Refund of part of the amount paid" , "Beater (anag) -- partial refund" .)