A fair demeanour returns after cold nosh here (9)
I believe the answer is:
cafeteria
'nosh here' is the definition.
'a fair demeanour returns after cold' is the wordplay.
'fair' becomes 'fete' (I've seen this before**).
'demeanour' becomes 'air' (air is a kind of demeanour).
'returns' says the letters should be written backwards.
'after' means one lot of letters go next to another.
'cold' becomes 'c' (eg on taps).
'air' reversed gives 'ria'.
'a'+'fete'+'ria'='afeteria'
'afeteria' after 'c' is 'CAFETERIA'.
(Other definitions for cafeteria that I've seen before include "cheap restaurant" , "where food can be picked up" , "Self-help facility" , "Canteen" , "place of refreshment" .)