Sharp-tasting (6)
I believe the answer is:
acidic
This clue is a double definition.
'sharp' is the first definition.
(I've seen this before)
'tasting' is the second definition.
(I have seen 'Sharp tasting' mean 'acidic' so perhaps 'tasting' could also mean 'acidic')
(Other definitions for acidic that I've seen before include "scathing?" , "Sharp-tasting, sour" , "Cutting" , "Vinegary" , "Tart, sour" .)