The most common and most likely answer to this crossword clue is the 9 letter word MISCREANT
I've seen this crossword clue in The Times
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More clues leading to the result MISCREANT
- Perpetrator of terrible crimes — a soldier, possibly
- Offender is soldier perhaps behind nasty crimes
- Criminal misrepresented crimes by soldier?
- Racist men unfortunately behaving unlawfully
- . Villain in car Met ordered around front of Subaru
- Funny type endless involved in moneymaking enterprise, a bad guy
- Villain‘s crimes upset social worker
- Short shriek contained by perfect little terror
- Worker supporting varied crimes – petty offender?
- Bad boy‘s crimes affected social worker
Buddy explains!

The straight part
We know that "behaving unlawfully" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case behaving unlawfully = miscreant.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 MISCREANT mean?
MISCREANT noun- One who has behaved badly, or illegally.
- One not restrained by moral principles; an unscrupulous villain.
- One who holds a false religious belief; a misbeliever.
- Lacking in conscience or moral principles; unscrupulous.
- Holding an incorrect religious belief.