The most common and most likely answer to this crossword clue is the 10 letter word TRIATHLONS
I've seen this crossword clue in The Daily Telegraph
T
R
I
A
T
H
L
O
N
S
Buddy explains!
The straight part
We know that "races" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case races = triathlons.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 TRIATHLONS mean?
TRIATHLONS noun- An athletics event in which contestants compete in swimming, cycling and running in turn.
- A former Olympic athletics event in which contestants compete in long jump, shot put, and 100-yard dash.
- Generally, a sports event in which contestant compete in a combination of three sports.