Maxim or Henry quitting information superhighway (5)

I believe the answer is:

tenet

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'maxim' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for tenet that I've seen before include "Doctrine held to be true" , "A religious doctrine proclaimed as true without proof" , "Rule" , "Item of belief" , "Belief held as true" .)

I've seen this clue in The Times.

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