Club mixer (4)
I believe the answer is:
soda
'club mixer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for soda that I've seen before include "Soft drink" , "Sodium carbonate" , "Splash served with some spirits" , "Variety of pop" , "Alkaline substance used in cleaning, drinks etc" .)