Derby or beret (3)
I believe the answer is:
hat
I believe this is a double definition.
'derby' is the first definition.
(I've seen this in another clue)
'beret' is the second definition.
(thesaurus)
(Other definitions for hat that I've seen before include "Cloche or fez?" , "Accessory" , "Headwear" , "One to cover head" , "Eg, bowler" .)