The most common and most likely answer to this crossword clue is the 10 letter word GERIATRICS
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "old people" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old people = geriatrics.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 GERIATRICS mean?
GERIATRICS noun- The branch of medicine that focuses on health promotion and the prevention and treatment of disease and disability in later life. The term itself can be distinguished from gerontology, which is the study of the aging process itself.
- An old person.