Strange rationale for one causing estrangement (9)

I believe the answer is:

alienator

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'one causing estrangement' is the definition.
The definition suggests a singular noun which matches the answer.

'strange rationale' is the wordplay.
'strange' indicates an anagram.
'rationale' with letters rearranged gives 'ALIENATOR'.

'for' is the link.

Can you help me to learn more?

(Other definitions for alienator that I've seen before include "Off-putting type" , "one who repels" , "Causer of estrangement" .)

I've seen this clue in The Independent.

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