The most common and most likely answer to this crossword clue is the 10 letter word DISHONESTY
I've seen this crossword clue in The Daily Telegraph
D
I
S
H
O
N
E
S
T
Y
More clues leading to the result DISHONESTY
- Beautiful girl has one filthy place to live in — it's not fair
- E.g. stealing bit of crockery with a single dirty spot
- Crime attractive? Individual's getting time inside
- Improbity in the synod is out of order
- Lying in bed, I shone stylishly
- Single saint taken in by attractive fraud
- Fiddling practice?
- Yes, this Don can be tricky — it’s not fair!
- Cheating — could be attractive keeping notes exchanged
- Battered Tyson hides lack of sincerity
Buddy explains!

The straight part
We know that "it’s not fair" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s not fair = dishonesty.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 DISHONESTY mean?
DISHONESTY noun- The characteristic or condition of being dishonest.
- An act which is fraudulent or otherwise dishonest.