Pinch pin back (3)
I believe the answer is:
nip
'pinch' is the definition.
(nip can mean to pinch or bite)
'pin back' is the wordplay.
'back' says the letters should be written in reverse.
'pin' written backwards gives 'NIP'.
(Other definitions for nip that I've seen before include "Pinch using pin" , "Dram of spirits" , "Pinch sharply, perhaps in the bud" , "Feeling cold" , "Pinch; bite" .)