Backhander, payoff (5)
I believe the answer is:
bribe
This clue is a double definition.
'backhander' is the first definition.
(I've seen this before)
'payoff' is the second definition.
(synonyms)
(Other definitions for bribe that I've seen before include "Bung" , "Illegal inducement" , "Kickback" , "Sweetener, inducement" , "Sop" .)