Religious attire - black attire, restyled (7)
I believe the answer is:
biretta
'religious attire' is the definition.
(hat worn by a Catholic clergyman)
'black attire restyled' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'restyled' indicates an anagram.
'attire' is an anagram of 'iretta'.
'b'+'iretta'='BIRETTA'
(Other definitions for biretta that I've seen before include "Cardinal's red cap" , "Battier (anag.)" , "Roman Catholic priest's cap" , "Clerical headgear" , "Square cap worn by Roman Catholic clergy" .)