The most common and most likely answer to this crossword clue is the 8 letter word EMPLOYEE
I've seen this crossword clue in The Daily Telegraph
E
M
P
L
O
Y
E
E
Buddy explains!
The straight part
We know that "One has a job to be one" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one has a job to be one = employee.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 EMPLOYEE mean?
EMPLOYEE noun- An individual who provides labor to a company or another person.