Beret or derby (3)
I believe the answer is:
hat
I believe this is a double definition.
'beret' is the first definition.
(thesaurus)
'derby' is the second definition.
(I've seen this in another clue)
(Other definitions for hat that I've seen before include "One to cover head" , "Head-covering" , "Cloche or fez?" , "e.g. Pork pie" , "Headgear decoration" .)