The most common and most likely answer to this crossword clue is the 9 letter word CAREERIST
I've seen this crossword clue in The Times
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More clues leading to the result CAREERIST
Buddy explains!
The straight part
We know that "person determined to get on" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case person determined to get on = careerist.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 CAREERIST mean?
CAREERIST noun- A person who pursues the advancement of their career at the expense of other values.
- A person who takes a job, especially in the military, for a long time rather than temporarily.
- Of or pertaining to such a person or way of life