Study exquisite pen (7)
I believe the answer is:
confine
'pen' is the definition.
(I've seen this in another clue)
'study exquisite' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'exquisite' becomes 'fine' (synonyms).
'con'+'fine'='CONFINE'
(Other definitions for confine that I've seen before include "Imprison" , "Keep within limits" , "Limit" , "Shut in" , "Restrict (to an area)" .)