At home, I love having emperor round – but it's not very spacious (12)
I believe the answer is:
incommodious
'at home i love having emperor round but' is the definition.
I can't tell whether this defines the answer.
'not very spacious' is the wordplay.
'not very' becomes 'in' (I can't explain this - if you can you should give a lot more credence to this answer).
'spacious' becomes 'commodious' ('commodious' can be similar in meaning to 'spacious').
'in'+'commodious'='INCOMMODIOUS'
'it's' is the link.
Can you help me to learn more?
(Another definition for incommodious that I've seen is " Cramped - inconvenient".)