Pacific island, genuine and raw, deposing King in rebellion (3,6)
I believe the answer is:
new guinea
'pacific island' is the definition.
(I've seen this before)
'genuine and raw deposing king in rebellion' is the wordplay.
'and' says to put letters next to each other.
'deposing' suggests deleting specific letters.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'in rebellion' is an anagram indicator.
'genuine'+'raw'='genuineraw'
'genuineraw' with 'r' taken away is 'genuineaw'.
'genuineaw' with letters rearranged gives 'NEW GUINEA'.
(Other definitions for new guinea that I've seen before include "Island in the Western Pacific" , "Pacific island, the world's second largest" , "divided island" , "Papua - - - -" .)