'Predated' now 'pronated' because of this boffin (6)

I believe the answer is:

edison

'boffin' is the definition.
(inventor Thomas Edison)

I cannot understand how the rest of the clue works.

(Other definitions for edison that I've seen before include "Inventor of the light bulb" , "He came up with microphone" , "Thomas ......, famous American inventor" , "Thomas --, US?inventor" , "Onside with great American inventor" .)

I've seen this clue in The Guardian.

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