Helps at a heist (5)
I believe the answer is:
abets
'helps at a heist' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for abets that I've seen before include "Helps (someone to commit crime)" , "Assists dealer, say" , "Aids in wrong-doing" , "Assists in wrongdoing" , "Assists or encourages" .)