Fusses over drink (4)
I believe the answer is:
soda
'drink' is the definition.
(soda is a kind of drink)
'fusses over' is the wordplay.
'fusses' becomes 'ados' ('ado' can be a synonym of 'fuss').
'over' says the letters should be written backwards.
'ados' written backwards gives 'SODA'.
(Other definitions for soda that I've seen before include "fizz" , "Alkaline substance used in cleaning, drinks etc" , "In the US, a sweet fizzy drink" , "Fizzy drink - chemical compound" , "pressurised liquid" .)