Assist in wrongdoing (4)
I believe the answer is:
abet
'assist in wrongdoing' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for abet that I've seen before include "Encourage or assist (someone) to commit crime" , "Help to do something wrong" , "Assist in some nefarious activity" , "Aid (in wrongdoing)" , "Crookedly endorse" .)