Is 'Any One' a Single Word?
'Any one' (with space between the words 'any' and 'one') is not an indefinite pronoun. It is a noun phrase comprised of two separate words 'any' and 'one'. It refers to one of the two or more things or people.
It is not very commonly-used in English language.
'Anyone' is an indefinite pronoun referring to an unspecified person. It means any person at all no matter who. More often than not, you will see 'anyone' with this spelling.
He is kind to