Posh bloke is a Tory bastard? Not unknown (6)

I believe the answer is:

aristo

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'posh bloke' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'is a tory bastard? not unknown' is the wordplay.
'tory' becomes 'r' (abbreviation for right).
'bastard?' indicates an anagram (bastard can mean impure or mixed).
'not unknown' becomes 'to' (I can't explain this - if you can you should give a lot more credence to this answer).
'is'+'a'+'r'='isar'
'isar' anagrammed gives 'aris'.
'aris'+'to'='ARISTO'

Can you help me to learn more?

(Other definitions for aristo that I've seen before include "one of the best" , "Nob" , "Owned by the state" , "Noble (abbrev.)" , "Member of the nobility (abbr)" .)

I've seen this clue in The Guardian.

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