Catholic girl shows style (5)
I believe the answer is:
class
'style' is the definition.
(thesaurus)
'catholic girl' is the wordplay.
'catholic' becomes 'c' (abbreviation as in RC for Roman Catholic).
'girl' becomes 'lass' (lass is a kind of girl**).
'c'+'lass'='CLASS'
'shows' acts as a link.
(Other definitions for class that I've seen before include "Genre" , "High quality" , "showing stylish excellence" , "Group of students" , "Study group" .)