Happy to have varied opinions but clearly derogate age rise (5,2,8)

I believe the answer is:

agree to disagree

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'happy to have varied opinions but clearly derogate age rise' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'happy to have varied opinions but clearly derogate age rise' is the wordplay.
'derogate age rise' can be anagrammed to 'AGREE TO DISAGREE'.
However, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Another definition for agree to disagree that I've seen is " Drop unresolved argument".)

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

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