The most common and most likely answer to this crossword clue is the 10 letter word HORSEFLESH
I've seen this crossword clue in The Daily Telegraph
H
O
R
S
E
F
L
E
S
H
Buddy explains!

The straight part
We know that "the equine race" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the equine race = horseflesh.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 HORSEFLESH mean?
HORSEFLESH noun- The flesh of a horse; horse meat.
- Horses collectively, with reference to driving, riding, or racing.
- A species of Bahama mahogany, Lysiloma sabicu and Lysiloma latisiliquum.
- Of the colour of horseflesh; of a peculiar reddish-brown hue.