Sweet turning up a little more acidic (4)
I believe the answer is:
aero
'sweet' is the definition.
(Aero is a brand of chocolate bar)
'turning up a little more acidic' is the wordplay.
'turning up' says the letters should be written in reverse.
'a little' says the answer is hidden in the clue (a little bit of the clue).
'orea' is hidden in the letters of 'more acidic'.
'orea' backwards is 'AERO'.
(Other definitions for aero that I've seen before include "Prefix meaning air or aircraft" , "bar" , "Prefix denoting air" .)