Article required in escape from window (8)
I believe the answer is:
fanlight
'window' is the definition.
(fanlight is a kind of window)
'article required in escape' is the wordplay.
'article' becomes 'an' (indefinite article).
'required in' is an insertion indicator.
'escape' becomes 'flight' ('flight' can be a synonym of 'escape'**).
'an' going within 'flight' is 'FANLIGHT'.
'from' acts as a link.
(Other definitions for fanlight that I've seen before include "It enables us to see" , "Windows above a door" , "kind of window" , "Rectangular window over a door" , "opening over the door" .)