Vinegar-based (6)
I believe the answer is:
acetic
'vinegar-based' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for acetic that I've seen before include "Colourless pungent acid" , "Vinegar-like" , "Type of acid derived from vinegar" , "Tasting like vinegar" , "Like the acid in vinegar" .)