Room seen through the French window (7)
I believe the answer is:
lattice
'window' is the definition.
(type of window)
'room seen through the french' is the wordplay.
'room' becomes 'attic' (I've seen this before**).
'seen through' is an insertion indicator (I've seen this in other clues).
'the french' becomes 'le'.
'attic' inserted into 'le' is 'LATTICE'.
(Other definitions for lattice that I've seen before include "Arrangement with bars" , "Network of crossed laths" , "Open framework in pattern" , "Openwork structure" , "Regular arrangement" .)