Acting as regent to cut off relations (8)

I believe the answer is:

estrange

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'to cut off relations' is the definition.
I can't tell whether this definition defines the answer.

'acting as regent' is the wordplay.
'as regent' anagrams to 'ESTRANGE'.
However, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for estrange that I've seen before include "As Regent (anag.)" , "Make bad friends with sergeant" , "Divorce" , "Forfeit friendship of, make hostile" , "Cause to be alienated" .)

I've seen this clue in the Sydney Morning Herald.

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