Painters, possibly, inside fitting gaff (9)
I believe the answer is:
apartment
'gaff' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for apartment that I've seen before include "property" , "Suite of rooms to live in" , "pad" , "Flat (mainly US)" , "Penthouse" .)