Help with wrongdoing (4)
I believe the answer is:
abet
'help with wrongdoing' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for abet that I've seen before include "Beat up by way of help" , "Crookedly endorse" , "Help in wrongdoing" , "Aid and assist" , "Aid (in wrongdoing)" .)