Reportedly, sovereign power knocked for six (6)
I believe the answer is:
thrown
'knocked for six' is the definition.
'reportedly sovereign power' is the wordplay.
'reportedly' shows a homophone (sound like).
'sovereign power' becomes 'throne' (I've seen this in another clue).
'throne' sounds like 'THROWN'.
(Other definitions for thrown that I've seen before include "Rabindranath ---, Indian sage" , "Unsettled" , "Disconcerted, confused" , "put out" , "Defeated" .)