Room’s window having no frame (5)
I believe the answer is:
attic
'room's' is the definition.
(I've seen this before)
'window having no frame' is the wordplay.
'window' becomes 'lattice' (type of window).
'having no frame' indicates the central letters (the frame could mean the outside letters).
The middle letters of 'lattice' are 'ATTIC'.
(Other definitions for attic that I've seen before include "Small room at the top" , "Classically elegant" , "Top level" , "Top apartment" , "Ancient Greek dialect - top room" .)