An unparticular person (6)

I believe the answer is:

anyone

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'an unparticular person' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'unparticular person' is the wordplay.
'unparticular' becomes 'any' (I can't explain this - if you can you should believe this answer much more).
'person' becomes 'one' (I've seen this in other clues).
'any'+'one'='ANYONE'

Can you help me to learn more?

(Other definitions for anyone that I've seen before include "Nobody specified" , "Anybody at all" , "No particular person" , "An unspecified person or persons" , "A random person" .)

I've seen this clue in The Guardian and The Globe and Mail.

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