Warmer in bed in close relationship (7)
I believe the answer is:
nightie
'warmer in bed' 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?
'close relationship' is the wordplay.
'close' becomes 'nigh' (similar in meaning).
'relationship' becomes 'tie' (tie is a kind of relationship).
'nigh'+'tie'='NIGHTIE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for nightie that I've seen before include "Late shift perhaps" , "Loose dress worn in bed" , "Sleepwear" , "Bedtime habit" , "Item worn by women" .)