Unscrupulous (6)
I believe the answer is:
amoral
'unscrupulous' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for amoral that I've seen before include "Without sense of right and wrong" , "Lacking a sense of right and wrong" , "Unprincipled" , "Ignoring ethical considerations" , "Having no standards of right or wrong" .)