Reportedly something that beats a mature male deer (4)

I believe the answer is:

hart

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'mature male deer' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for hart that I've seen before include "providing material for Richard Rodgers?" , "Stag" , "Ruminative type" , "Male deer; Rodgers collaborator" , "Adult male red deer" .)

I've seen this clue in The Times.

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