Regular advance covers most of audition for old leading lady (9)

I believe the answer is:

matriarch

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

I can't explain the rest of the clue.

(Other definitions for matriarch that I've seen before include "Woman dominant" , "Powerful older woman" , "Dominating female" , "venerable old lady" , "Dominant female" .)

I've seen this clue in The Telegraph.

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