Crossword Genius

Revocation of a legacy, one associated with Piedmont organisation (9)

Ross

I believe the answer is:

ademption

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'revocation of a legacy' is the definition.
The definition suggests a singular noun which matches the answer.

'one associated with piedmont organisation' is the wordplay.
'one' becomes 'a'.
'associated with' means one lot of letters go next to another.
'organisation' indicates anagramming the letters.
'piedmont' with letters rearranged gives 'demption'.
'a'+'demption'='ADEMPTION'

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I've seen this clue in The Guardian.
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