Sauce or garnish for food (7)
I believe the answer is:
topping
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">sauce</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(sauce is a type of topping)</span><br/ ><br/ >'<span class="explanation-format__original">garnish for food</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for topping that I've seen before include "garnish for food" , "Polishing off" , "Sauce; excellent (dated)" , "Garnish - splendid!" , "Absolutely excellent!" .)