Partner of aid (4)
I believe the answer is:
abet
'partner of aid' 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 "Incite (to commit an offence)" , "Assist criminally" , "Aid (a criminal)" , "Aid and help, perhaps in crime" , "Assist (in wrongdoing)" .)