Small fuss over drink (4)
I believe the answer is:
soda
'drink' is the definition.
(soda is a kind of drink)
'small fuss over' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'fuss' becomes 'ado' ('ado' can be a synonym of 'fuss').
'over' says the letters should be written in reverse.
'ado' reversed gives 'oda'.
's'+'oda'='SODA'
(Other definitions for soda that I've seen before include "Splash served with some spirits" , "Soft drink" , "Whisky mixer" , "Alkaline substance used in cleaning, drinks etc" , ""Splashed" drinks mixer" .)