Tweeter, perhaps one MP’s must heed (7)

I believe the answer is:

speaker

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'tweeter perhaps' is the definition.
(tweeter is a kind of speaker)

I don't understand the remainder of the clue.

(Other definitions for speaker that I've seen before include "Orator" , "He asks for order" , "Officer of House of Commons" , "Parliamentary presiding officer" , "audio equipment" .)

I've seen this clue in The Times.

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