Bitter (4)
'bitter' is the definition.
(synonyms)
This is all the clue.
(Other definitions for acerbic that I've seen before include "Cutting" , "Bitter in taste -- harsh in tone" , "Biting" , "Tasting sour or caustic in speech" , "Sharp, forthright" .)
(Other definitions for rancid that I've seen before include "Smelling or tasting of stale fat" , "Smelling bad like stale fat" , "Unpleasantly stale" , "Like fat that's gone off" , "Putrid" .)
'bitter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for acidic that I've seen before include "Sarcastic or sour" , "Sharp-tasting, sour" , "Vinegary" , "Containing a sour-tasting substance" , "scathing?" .)
(Other definitions for acid that I've seen before include "Corrosive fluid" , "Sharp - tart - kind of house party" , "Sour - LSD" , "Sour, sharp-tasting" , "Cutting" .)
'bitter' is the definition.
(tart can mean bitter-tasting)
This is all the clue.
(Other definitions for tart that I've seen before include "Open cake with jam etc" , "sour type of pie" , "Sharp on the tongue" , "perhaps rather sharp" , "Professional woman" .)
'bitter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sour that I've seen before include "Rancid or tart" , "Acid tasting" , "Acid - bitter" , "Acid, tart" , "Bitter, tart" .)