Disapproving sounds at alcohol, say (4)
I believe the answer is:
boos
'disapproving sounds' is the definition.
(I've seen this in another clue)
'alcohol say' is the wordplay.
'alcohol' becomes 'booze' (booze is a kind of alcohol).
'say' shows a homophone (sound like).
'booze' is a homophone of 'BOOS'.
'at' is the link.
(Other definitions for boos that I've seen before include "Shows disapproval" , "Catcalls" , "Shouts of derision" , "Sounds of disapproval" , "Shouts of disapproval" .)