Extremely cold beer (6)
I believe the answer is:
bitter
I believe this is a double definition.
'extremely cold' is the first definition.
(bitterly cold)
'beer' is the second definition.
(bitter is a type of beer)
(Other definitions for bitter that I've seen before include "Sour taste or resentful" , "Not sweet; very cold" , "Resentful and cynical" , "Sharp-tasting or resentful" , "Kind of British beer" .)