Exceptional religious studies by artist (4)
I believe the answer is:
rare
'exceptional' is the definition.
(thesaurus)
'religious studies by artist' is the wordplay.
'religious studies' becomes 're' (abbreviation for Religious Education).
'by' means one lot of letters go next to another.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
're' after 'ra' is 'RARE'.
(Other definitions for rare that I've seen before include "like gold dust" , "Very lightly cooked, meat say" , "Still red inside (as hens' teeth?)" , "Scarcely seen" , "Choice - lightly cooked - thin" .)