Treason would ruin this politician (7)

I believe the answer is:

senator

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'this politician' is the definition.
(I've seen this before)

'treason would ruin' is the wordplay.
'treason' can be anagrammed to 'SENATOR'.
Though, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for senator that I've seen before include "Member of Upper House engaged in treason" , "US/Roman politician" , "Roman politician" , "Politician involved in treason" , "Member of the Second House" .)

I've seen this clue in the Evening Standard.

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