Mongrel mutt took cheap condiment (6,7)
I believe the answer is:
tomato ketchup
'condiment' is the definition.
(tomato ketchup is a kind of condiment)
'mongrel mutt took cheap' is the wordplay.
'mongrel' indicates an anagram (I've seen this in other clues).
'mutt'+'took'+'cheap'='mutttookcheap'
'mutttookcheap' with letters rearranged gives 'TOMATO KETCHUP'.
(Other definitions for tomato ketchup that I've seen before include "Red sauce" , "Sauce popular with chips" .)