Bathrobe securer (4)
I believe the answer is:
sash
'bathrobe securer' 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 "Frame for a windowpane" , "Ribbon as a symbol of rank" , "Band - scarf" , "seen hanging around Miss World?" , "type of cord?" .)