Stylish Catholic rings student (4)
I believe the answer is:
cool
'stylish' is the definition.
'catholic rings student' is the wordplay.
'catholic' becomes 'c' (abbreviation as in RC for Roman Catholic).
'rings' becomes 'oo' (multiple circles).
'student' becomes 'l' (**).
'c'+'oo'+'l'='COOL'
(Other definitions for cool that I've seen before include "chic" , "Moderately cold" , "Level-headed" , "Calm and unemotional" , "Hip - not warm" .)