Dull to allow little accommodation (7)
I believe the answer is:
flatlet
'little accommodation' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'dull to allow' is the wordplay.
'dull' becomes 'flat' (similar in meaning).
'to allow' becomes 'let' ('let' can be a synonym of 'allow').
'flat'+'let'='FLATLET'
Can you help me to learn more?
(Other definitions for flatlet that I've seen before include "A tiny apartment" , "Tiny living quarters" .)