Flat couple acquires is only triple-glazed at the front (10)
I believe the answer is:
maisonette
'triple-glazed at the front' is the definition.
I can't tell whether this defines the answer.
'flat couple acquires is only' is the wordplay.
'flat couple' becomes 'matte' (I can't explain this - if you can you should believe this answer much more).
'acquires' is an insertion indicator.
'only' becomes 'one' (synonyms).
'is'+'one'='isone'
'matte' placed around 'isone' is 'MAISONETTE'.
Can you help me to learn more?
(Other definitions for maisonette that I've seen before include "Self-contained living accommodation on two floors" , "dwelling place" , "starter home?" , "small property" , "possible place to live" .)