Pub mainly warm -- and good nuts (7)
I believe the answer is:
barking
'nuts' is the definition.
(both can informally mean mad)
'pub mainly warm and good' is the wordplay.
'pub' becomes 'bar' (both are drinking establishments).
'mainly' means to remove the last letter.
'warm' becomes 'kind' (synonyms).
'and' says to put letters next to each other.
'good' becomes 'g' (abbreviation).
'kind' with its last letter taken away is 'kin'.
'bar'+'kin'+'g'='BARKING'
(Other definitions for barking that I've seen before include "Completely mad" , "Crazy - yapping" , "What Battersea resident may be doing" , "up the pole" , "Dog may be" .)