The most common and most likely answer to this crossword clue is the 7 letter word CHUTNEY
I've seen this crossword clue in The Guardian
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Buddy explains!
The straight part
We know that "Relish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case relish = chutney.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.
What does CHUTNEY mean?
CHUTNEY noun- A sweet or savory but usually spicy condiment, originally from eastern India, made from a variety of fruits and/or vegetables, often containing significant amounts of fresh green or dried red chili peppers.
- A style of Indo-Caribbean music from the West Indies, associated especially with Trinidad and Tobago.