Grape sugar (8)
I believe the answer is:
dextrose
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grape sugar</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for dextrose that I've seen before include "sweet stuff" , "sweetener" , "Form of sugar, in honey, say" , "Form of glucose" .)