The most common and most likely answer to this crossword clue is the 7 letter word ONANISM
I've seen this crossword clue in The Guardian
O
N
A
N
I
S
M
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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 ONANISM mean?
ONANISM noun- Masturbation.
- Ejaculating outside the vagina during intercourse; (the performing of) coitus interruptus.