Cap of Catholic clergy (7)
I believe the answer is:
biretta
'cap of catholic clergy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for biretta that I've seen before include "Clerical headgear" , "Roman Catholic priest's cap" , "ecclesiastical headgear" , "religious headwear" , "Battier (anag.)" .)