Not a particular person (7)

I believe the answer is:

someone

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'person' is the definition.
(synonyms)

'not a particular' is the wordplay.
'not' becomes 'some' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a particular' becomes 'one'.
'some'+'one'='SOMEONE'

Can you help me to learn more?

(Other definitions for someone that I've seen before include "big cheese" , "A person (maybe of importance)" , "Unspecified human being" , "individual" , "An unknown person" .)

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

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