A religious image I study (4)
I believe the answer is:
icon
'a religious image' is the definition.
(I've seen this in another clue)
'i study' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'i'+'con'='ICON'
(Other definitions for icon that I've seen before include "Holy image or symbol on computer screen" , "Something on computer screen" , "Sacred painting or representative figure" , "Small image on computer screen" , "Sacred painting or representitive figure" .)