Trim, as a photo (4)
I believe the answer is:
crop
'trim as a photo' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for crop that I've seen before include "hair style" , "Expanded part of bird's throat" , "Type of whip" , "Whip with loop instead of lash" , "Harvest or kind of whip" .)