The most common and most likely answer to this crossword clue is the 7 letter word ATHLETE
I've seen this crossword clue in The Times
A
T
H
L
E
T
E
More clues leading to the result ATHLETE
- A permit received by the track and field competitor?
- Olympian at home cleared out to accommodate tenancy
- Sportsman's father not taking sides, accepting foul shot
- Complaint to hotel — feast is awful
- Runner let into swimming heat
- The tale involved sportsperson
- Competitor in lather out of bounds having caught obstacle
- Runner's complaint? Trainer will cover it
- Two articles about permit for sportsman
- Complaint that feels too contrived?
Buddy explains!

The straight part
We know that "Runner" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case runner = athlete.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 ATHLETE mean?
ATHLETE noun- A participant in a group of sporting activities which includes track and field, road running, cross country running and racewalking.
- A person who actively participates in physical sports, especially with great skill; a sportsperson.
- An exceptionally physically fit person.