Inventor upsetting no faction (6)
I believe the answer is:
edison
'inventor' is the definition.
(I know this)
'upsetting no faction' is the wordplay.
'upsetting' shows that the letters should be reversed in order.
'faction' becomes 'side' (one side in a conflict or controversy).
'no'+'side'='noside'
'noside' reversed gives 'EDISON'.
(Other definitions for edison that I've seen before include "Thomas Alva -, US inventor" , "Incandescent light inventor" , "Thomas --, US?inventor" , "Inventor's" , "Inventor with over 1,000 US patents to his name, d. 1931" .)