The most common and most likely answer to this crossword clue is the 9 letter word EXPLETIVE
I've seen this crossword clue in The Times
E
X
P
L
E
T
I
V
E
More clues leading to the result EXPLETIVE
- Telex VIP sent with English obscenity
- Former PL team’s left wing back dives, missing header and second 12 across?
- Its characters often become stars
- Former prince allowed Cyclops possesses a Richard Nixon speciality
- Telex VIP sent with ultimately vile obscenity
- Old cat or dog I have, catching fifty rats, say?
- Former favourite compiler’s receiving large curse
- It’s said, but often censored
- It’s topless love. The compiler’s fifty — that’s taken in with curse!
- Evil pet buckled under Biblical book’s earthy language
Buddy explains!

The straight part
We know that "obscenity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case obscenity = expletive.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 EXPLETIVE mean?
EXPLETIVE noun- A profane, vulgar term, notably a curse or obscene oath.
- A word without meaning added to fill a syntactic position.
- A word that adds to the strength of a phrase without affecting its meaning.
- Serving to fill up, merely for effect, otherwise redundant.
- Marked by expletives (phrase-fillers).