Be powered by what overlong speakers do? (5)

I believe the answer is:

runon

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'what overlong speakers do?' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'be powered' is the wordplay.
'be' becomes 'run' (running is a kind of being).
'powered' becomes 'on' (I can't explain this - if you can you should give a lot more credence to this answer).
'run'+'on'='RUNON'

'by' is the link.

Can you help me to learn more?

(Another definition for runon that I've seen is " not using paragraphs?".)

I've seen this clue in The Times.

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