Unfashionable drink sounds an unlikely winner (8)
I believe the answer is:
outsider
'an unlikely winner' is the definition.
'outsider' can be an answer for 'winner' (I have seen 'Improbable winner' mean 'outsider' so perhaps 'winner' could also mean 'outsider'). I am not certain of the 'an unlikely' bit.
'unfashionable drink sounds' is the wordplay.
'unfashionable' becomes 'out' (synonyms).
'drink sounds' becomes 'sider' (I can't explain this - if you can you should give a lot more credence to this answer).
'out'+'sider'='OUTSIDER'
Can you help me to learn more?
(Other definitions for outsider that I've seen before include "Not one of the favourites" , "Detours I make as person excluded from group" , "expected to be unsuccessful" , "Someone not accepted by society" , "Contestant who hasn't much of a chance" .)