Criminally assist (4)
I believe the answer is:
abet
'criminally assist' 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 (anag.)" , "Aid and help, perhaps in crime" , "Beat up by way of help" , "Assist (in wrongdoing)" , "helpful" .)