The most common and most likely answer to this crossword clue is the 6 letter word WORKER
I've seen this crossword clue in Financial Times
W
O
R
K
E
R
Buddy explains!

The straight part
We know that "One has a job" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one has a job = worker.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 WORKER mean?
WORKER noun- A person who performs labor for a living, especially manual labor.
- A nonreproductive social insect, such as ant, bee, termite, or wasp.
- A thread performing one instance of a particular task within a program.