Motivated by bribery (5)
I believe the answer is:
venal
'motivated by bribery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for venal that I've seen before include "can be bought cheaply" , "easily bribed" , "motivated by corruption" , "Open to bribes" , "'Corrupt, open to bribery (5)'" .)