Possibly shrink from believer grabbing cuff (9)
I believe the answer is:
therapist
'possibly shrink' is the definition.
(informal term for a therapist or psychiatrist)
'believer grabbing cuff' is the wordplay.
'believer' becomes 'theist' (theist is a kind of believer).
'grabbing' means one lot of letters goes inside another.
'cuff' becomes 'rap' (both can mean to hit).
'theist' enclosing 'rap' is 'THERAPIST'.
'from' is the link.
(Other definitions for therapist that I've seen before include "One giving treatment" , "One treating mental disorders" , "See 21" , "Who can soothe" , "Help" .)