Headgear container (6)
I believe the answer is:
hatbox
'headgear container' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for hatbox that I've seen before include "Headgear container" , "Milliner's container" , "Ten-gallon container maybe" , "Container for headwear" , "Case for toppers" .)