The most common and most likely answer to this crossword clue is the 7 letter word CAREERS
C
A
R
E
E
R
S
Buddy explains!

The straight part
We know that "Runs/people’s professional lives" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case runs/people’s professional lives = careers.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 CAREERS mean?
CAREERS noun- One's calling in life; a person's occupation; one's profession.
- General course of action or conduct in life, or in a particular part of it.
- Speed.
- A jouster's path during a joust.
- A short gallop of a horse.
- The flight of a hawk.
- A racecourse; the ground run over.
- To move rapidly straight ahead, especially in an uncontrolled way.