The most common and most likely answer to this crossword clue is the 15 letter word UNSPORTSMANLIKE
I've seen this crossword clue in The Times
U
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More clues leading to the result UNSPORTSMANLIKE
- Dissimilar to cricketer perhaps, not cricket?
- Wears effeminate clothes below the belt
- Dirty mask until person’s changed
- Playing, a sulk’s prominent?
- Random insolent mark-ups? It’s just not cricket
- Sneaky, as most female athletes are essentially?
- Links son up with team, oddly taking on rugby, initially, not cricket
- Not following rules? PM Sunak silent or worried?
Buddy explains!

The straight part
We know that "Dissimilar to cricketer perhaps/not cricket?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dissimilar to cricketer perhaps/not cricket? = unsportsmanlike.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 UNSPORTSMANLIKE mean?
UNSPORTSMANLIKE adjective- Violating the accepted standards of sportsmanship