The most common and most likely answer to this crossword clue is the 11 letter word NATIONALITY
I've seen this crossword clue in The Times
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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 = nationality.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 NATIONALITY mean?
NATIONALITY noun- Membership of a particular nation or state, by origin, birth, naturalization, ownership, allegiance or otherwise.
- National, i.e. ethnic and/or cultural, character or identity.
- A people sharing a common origin, culture and/or language, and possibly constituting a nation-state.
- Political existence, independence or unity as a national entity.
- Nationalism or patriotism.