Use a crowbar on (3)
I believe the answer is:
pry
'use a crowbar on' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pry that I've seen before include "Peer impertinently, stick nose in" , "Snoop or lever" , "Stick one's nose in" , "Stick nose into other's business" , "Look inquisitively into private matters" .)