Angry noblewoman about to dump earl (3)

I believe the answer is:

mad

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'angry' is the definition.
(similar in meaning)

I don't understand the remainder of the clue.

(Other definitions for mad that I've seen before include "Roused to anger" , "Angry or insane" , "Aberrant" , "Crazy" , "(Of a dog) rabid" .)

I've seen this clue in The Sunday Times and The Times.

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