Life line? (6)
I believe the answer is:
career
This clue might be a double definition.
'life' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'line?' is the second definition.
(I know that career is a type of business)
Can you help me to learn more?
(Other definitions for career that I've seen before include "Run headlong at high speed" , "Working lifetime" , "'Occupation, profession (6)'" , "Lifetime's work" , "Move rapidly in progress through life" .)