The most common and most likely answer to this crossword clue is the 9 letter word FINALISTS
F
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Buddy explains!

The straight part
We know that "Last-round contestants" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case last-round contestants = finalists.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 FINALISTS mean?
FINALISTS noun- Somebody or something that appears in the final stage of a competition.
- A university student in his/her final year of study.