The most common and most likely answer to this crossword clue is the 8 letter word ASPIRANT
I've seen this crossword clue in Independent
A
S
P
I
R
A
N
T
More clues leading to the result ASPIRANT
- Ambitious, like country engaged in part
- Hopeful when old Rover briefly bears north
- Partisan in conflict, he seeks higher position
- One pursuing partisan struggles
- Ambitious partisan brought down
- Ambitious poisoner managed to inject it
- Candidate with a small point about ME country
- Showing ambition when I sound off about power
- Partisan, potentially one with ambition
- Wannabe a second artist covered in beer?
Buddy explains!

The straight part
We know that "one with ambition" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one with ambition = aspirant.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 ASPIRANT mean?
ASPIRANT noun- Someone who aspires to high office, etc.
- Seeking advancement.
- Striving for recognition.