Blissful Frenchman after draining Sancerre (6)
I believe the answer is:
serene
'blissful' is the definition.
(I've seen this in another clue)
'frenchman after draining sancerre' is the wordplay.
'frenchman' becomes 'rene' (common French name).
'after' is a charade indicator (letters next to each other).
'draining' says to hollow out the word (remove centre letters) (I've seen 'drained' mean this).
'sancerre' with its centre removed is 'se'.
'rene' after 'se' is 'SERENE'.
(Other definitions for serene that I've seen before include "Calm, peaceful, tranquil" , "Peaceful and unruffled" , "Calm and composed" , "Calm and relaxed" , "Calm and unclouded" .)