The most common and most likely answer to this crossword clue is the 9 letter word AMUSEMENT
I've seen this crossword clue in Independent
A
M
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E
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More clues leading to the result AMUSEMENT
- A source of inspiration intended, say, to provide delight
- Fun goddess the author's appended to a religious text
- Funny character encountered around noon, after morning exercise
- Diversion giving an essential cover for English soldiers?
- In exam, use menthol for fun
- Delight at me struggling with menus
- Diversion — something necessary to get round European soldiers
- A maiden to exploit men — time for fun!
- Enema must ruin enjoyment for 19
- Recreation ground — men’s team hosting United
Buddy explains!

The straight part
We know that "Diversion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case diversion = amusement.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 AMUSEMENT mean?
AMUSEMENT noun- Entertainment.
- An activity that is entertaining or amusing, such as dancing, gunning, or fishing.