Behave excessively, administering thrashing initially (4)

I believe the answer is:

beat

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'behave excessively administering thrashing initially' is the definition.
I can't judge whether this definition defines the answer.

'behave excessively administering thrashing initially' is the wordplay.
'initially' suggests taking the first letters.
The initial letters of 'behave excessively administering thrashing' is 'BEAT'.

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(Other definitions for beat that I've seen before include "Musical rhythm" , "Defeat; pulsate" , "Get the better of in competition" , "Defeat, strike" , "Strike repeatedly" .)

I've seen this clue in The Telegraph.

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