Actor Affleck (3)
I believe the answer is:
'actor affleck' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ben that I've seen before include "Mountain; man's name" , "inner room in Oban, say" , "High mountain (Scots)" , "Big . . . is a famous London clock-tower" , "Tropical tree" .)