Part of Batman's outfit (4)
I believe the answer is:
cowl
'part of batman's outfit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cowl that I've seen before include "form of protection?" , "Monk's hood or chimney covering" , "Hood for monk or chimney" , "Cover for monk or chimney" , "Monk's hood - chimney cover" .)