The most common and most likely answer to this crossword clue is the 7 letter word ABUSIVE
I've seen this crossword clue in Independent
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More clues leading to the result ABUSIVE
- Stuck behind a vehicle, this person's defamatory
- This person's on army's first vehicle in offensive
- Abandon barring women boarding vehicle? On the contrary, becoming insulting
- Foul-mouthed American quartet in Lincoln?
- Offensive American quartet appearing in Lincoln?
- A method of transport this writer’s vilifying
- Top-class coach not recorded dismissing league as insulting
- Insulting, using Ecstasy after measure of drink round American island
- Tail-gating a vehicle four finally become loud and coarse
- Insulting a coach, essentially cursing at very end of game
Buddy explains!

The straight part
We know that "Foul-mouthed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case foul-mouthed = abusive.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 ABUSIVE mean?
ABUSIVE adjective- Prone to treat someone badly by coarse, insulting words or other maltreatment; vituperative; reproachful; scurrilous.
- Tending to deceive; fraudulent.
- Tending to misuse; practising or containing abuse.
- Being physically or emotionally injurious; characterized by repeated violence or other abuse.
- Wrongly used; perverted; misapplied; unjust; illegal.
- Catachrestic.