Wide belt (4)
I believe the answer is:
sash
'wide belt' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sash that I've seen before include "Framework to hold the panes of a window" , "Type of sliding window" , "Piece of cloth round waist or shoulder" , "Style of window" , "Window frame - shoulder band" .)