The most common and most likely answer to this crossword clue is the 9 letter word OCCURRING
O
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The straight part
We know that "going on" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case going on = occurring.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 OCCURRING mean?
OCCURRING verb- To happen or take place.
- To present or offer itself.
- To come or be presented to the mind; to suggest itself.
- To be present or found.
- An instance of something occurring; an event or happening.
- (in combination) That occurs in a specified manner.