Reportedly predominant state (5)
I believe the answer is:
maine
'state' is the definition.
(Maine is an example)
'reportedly predominant' is the wordplay.
'reportedly' shows a homophone (sound like).
'predominant' becomes 'main' (main can mean predominant or principal).
'main' is a homophone of 'MAINE'.
(Other definitions for maine that I've seen before include "New England state" , "N. US Atlantic state" , "US state, capital Augusta (5)" , "NE US state" , "North-east American state" .)