Cummerbund (4)
I believe the answer is:
sash
'cummerbund' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sash that I've seen before include "Part of a window - decoration" , "Item of clothing - frame for glass" , "Band worn over shoulder or round waist" , "Waistband - type of window" , "Ribbon worn over the shoulder" .)