Cosy as can be, propose to drink half case of Chambertin (8)
I believe the answer is:
snuggest
'be propose to drink half case of chambertin' is the definition.
I can't judge whether this defines the answer.
'cosy as' is the wordplay.
'cosy' becomes 'snug' (synonyms).
'as' becomes 'gest' (I can't justify this - if you can you should give a lot more credence to this answer).
'snug'+'gest'='SNUGGEST'
'can' is the link.
Can you help me to learn more?
(Other definitions for snuggest that I've seen before include "Most warm" , "extremely tightly fitting" , "Most welcoming" .)