Acerbic (8)
I believe the answer is:
vinegary
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">acerbic</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for vinegary that I've seen before include "Peevish" , "Acerbic" , "Sour tasting" , "bitter" .)