Prune, with "off" (3)
I believe the answer is:
lop
'prune with off' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lop that I've seen before include "Hack" , "Cut away branches or twigs" , "Cut (e.g. branch off)" , "Cut off, tree branches say" , "Chop (off)" .)