The most common and most likely answer to this crossword clue is the 9 letter word OUTSIDERS
I've seen this crossword clue in The Guardian
O
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More clues leading to the result OUTSIDERS
Buddy explains!

The straight part
We know that "Likely losers/borderline personalities" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case likely losers/borderline personalities = outsiders.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 OUTSIDERS mean?
OUTSIDERS noun- One who is not part of a community or organization.
- A newcomer with little or no experience in an organization or community.
- A competitor or contestant who has little chance of winning; a long shot
- A pair of nippers for turning a key in a keyhole from the outside.