The most common and most likely answer to this crossword clue is the 8 letter word FINALIST
I've seen this crossword clue in Financial Times
F
I
N
A
L
I
S
T
More clues leading to the result FINALIST
- Healthy, inspiring new boxer's one who may win
- Fellow amongst celebrities is a potential winner
- Broken nail in hand of successful competitor
- Closed hand around broken nail, one of only two left?
- Fellow among celebrities, one with winning ways?
- Competitor if in last gets irritated
- Competitor following popular top-class celebrities
- The ultimate competitor
- One believing in completeness in time fails to adjust
- Football's leader database ropes in a champion in the interim
Buddy explains!

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