Tomato sauce (7)
I believe the answer is:
ketchup
'tomato sauce' is the definition.
(I've seen this before)
This is the entire clue.
(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" .)