Singular fuss about soft drink (4)
I believe the answer is:
soda
'soft drink' is the definition.
(I know that soft drink can be written as soda)
'singular fuss about' is the wordplay.
'singular' becomes 's' (abbreviation sometimes used in dictionaries).
'fuss' becomes 'ado' (synonyms).
'about' says the letters should be written backwards.
'ado' backwards is 'oda'.
's'+'oda'='SODA'
(Other definitions for soda that I've seen before include "Splash served with some spirits" , "for use with whisky?" , "kind of water" , "Sodium carbonate" , "In the US, a sweet fizzy drink" .)