The most common and most likely answer to this crossword clue is the 12 letter word ALTERNATIVES
I've seen this crossword clue in The Times
A
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More clues leading to the result ALTERNATIVES
Buddy explains!
The straight part
We know that "Possibilities" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case possibilities = alternatives.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 ALTERNATIVES mean?
ALTERNATIVES noun- A situation which allows a mutually exclusive choice between two or more possibilities; a choice between two or more possibilities.
- One of several mutually exclusive things which can be chosen.
- The remaining option; something available after other possibilities have been exhausted.
- Alternative rock