The most common and most likely answer to this crossword clue is the 8 letter word MARATHON
I've seen this crossword clue in The Times
M
A
R
A
T
H
O
N
More clues leading to the result MARATHON
- It’s something to run a temperature: no harm moving around outside
- Long-running drama, Farewell Monsieur, is back
- Hat Norma ruined in race
- In the long run, earl’s child follows revolutionary
- Man dying in bath with hot on somewhere in Greece
- Honourable to follow French revolutionary in the long run
- Honourable to support revolutionary in the long run
- French murder victim meeting death finally on race
- Long Island is shelter for grass house
- Race the old lady runs with unusual hat on
Buddy explains!

The straight part
We know that "race" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case race = marathon.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 MARATHON mean?
MARATHON noun- A 42.195 kilometre (26 mile 385 yard) road race.
- (by extension) Any extended or sustained activity.
- To run a marathon.
- To watch or read a large number of instalments of (a film, book, TV series, etc.) in one sitting.