The most common and most likely answer to this crossword clue is the 9 letter word DERAILING
I've seen this crossword clue in Financial Times
D
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R
A
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Buddy explains!

The straight part
We know that "this becoming a possibility" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this becoming a possibility = derailing.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 DERAILING mean?
DERAILING verb- To cause to come off the tracks.
- To come off the tracks.
- To deviate from the previous course or direction.
- To cause to deviate from a set course or direction; derange.
- The act by which something is derailed.