The most common and most likely answer to this crossword clue is the 6 plus 7 letter word TOMATO KETCHUP
I've seen this crossword clue in The Guardian
T
O
M
A
T
O
K
E
T
C
H
U
P
More clues leading to the result TOMATO KETCHUP
Buddy explains!
The straight part
We know that "Condiment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case condiment = tomato ketchup.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.