Tasteful way to make a vessel better (7)
I believe the answer is:
ketchup
'tasteful way' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'a vessel better' is the wordplay.
I cannot really see how this works, but
'vessel' could be 'ketch' (ketch is a kind of vessel) and 'ketch' is found within the answer.
The remaining letters 'up' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'to make' acts as a link.
Can you help me to learn more?
(Other definitions for ketchup that I've seen before include "Sauce made largely of tomatoes" , "Red sauce" , "Piquant sauce, often tomato based" , "Condiment" , "Spicy tomato sauce" .)