The most common and most likely answer to this crossword clue is the 10 letter word INJUSTICES
I've seen this crossword clue in The Times
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Buddy explains!
The straight part
We know that "They’re not fair" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they’re not fair = injustices.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 INJUSTICES mean?
INJUSTICES noun- Absence of justice; unjustice.
- Violation of the rights of another person or people.
- Unfairness; the state of not being fair or just.