Microphone inventor (6)
I believe the answer is:
'microphone inventor' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for edison that I've seen before include "Inventor with over 1,000 US patents to his name, d. 1931" , "Inventor of the carbon filament lamp, d. 1931" , "US scientist/inventor" , "inventive sort" , "scientist" .)