Tomato sauce (7)
I believe the answer is:
ketchup
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tomato sauce</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ketchup that I've seen before include "Spicy tomato sauce" , "Piquant sauce, often tomato based" , "Relish" , "Sauce made largely of tomatoes" , "Red sauce" .)