The most common and most likely answer to this crossword clue is the 10 letter word ENTHUSIASM
I've seen this crossword clue in The Times
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More clues leading to the result ENTHUSIASM
- Cook has minutes to find relish
- Passion unexpectedly unseats him
- Zest for excitement
- One doesn’t much care to be without it
- This person tucking into meat shuns prepared relish
- Regularly keen, therefore I am full of this, ultimately?
- False Messiah, nut showing zeal
- Anthem is played catching American fervour …
- Transport hit man uses with exuberance
- Warmth from the sun as I’m swimming
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 = enthusiasm.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 ENTHUSIASM mean?
ENTHUSIASM noun- Possession by a god; divine inspiration or frenzy.
- Intensity of feeling; excited interest or eagerness.
- Something in which one is keenly interested.