Border above window (6)
I believe the answer is:
pelmet
'border above window' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pelmet that I've seen before include "Valance board" , "Fringe over a curtain rail" , "Ornamental strip to conceal curtain-rail" , "Valance, fringe" , "Temple (anag)" .)