This lady's fair bid explored, one proving debatable (8,6)

I believe the answer is:

peroxide blonde

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'proving debatable' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'this lady's fair bid explored one' is the wordplay.
'bid explored one' anagrams to 'PEROXIDE BLONDE'.
But, I'm unsure how this is indicated.

Can you help me to learn more?

(Another definition for peroxide blonde that I've seen is " She's changed the locks".)

I've seen this clue in The Telegraph.

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