One sister nice in false pretences (13)

I believe the answer is:

insincerities

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'pretences' is the definition.
The definition and answer can be both human attributes as well as being plural nouns.
Maybe you can see an association between them that I can't see?

'one sister nice in false' is the wordplay.
'one' becomes 'i' (Roman numeral).
'false' indicates anagramming the letters.
'sister'+'nice'+'in'='sisternicein'
'sisternicein' anagrammed gives 'nsincerities'.
'i'+'nsincerities'='INSINCERITIES'

Can you help me to learn more?

I've seen this clue in The Telegraph.

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