It keeps sun and rain off a shop window (6)
I believe the answer is:
awning
'it keeps sun and rain off a shop window' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for awning that I've seen before include "Canvas cover over a shop entrance" , "Covering above a window or door" , "Sunshade" , "Canvas frame stretched as shelter against sun or rain" , "Canvas shelter as on shopfront" .)