Said they'd send up some Muscadet at six (6)
I believe the answer is:
stated
'said' is the definition.
('state' can be a synonym of 'say')
'up some muscadet at six' is the wordplay.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'detats' is hidden in the letters of 'muscadet at six'.
'detats' backwards is 'STATED'.
'they'd send' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for stated that I've seen before include "Close-fitting; drunk" , "Put in words, said" , "Said firmly, averred" , "Expressed, detailed" , "Declared as fact" .)