Herod's new island (6)
I believe the answer is:
rhodes
'island' is the definition.
(Greek island)
'herod's new' is the wordplay.
'new' is an anagram indicator.
'herods' with letters rearranged gives 'RHODES'.
(Other definitions for rhodes that I've seen before include "British financier and coloniser in southern Africa, d. 1902" , "Dock for undersea craft" , "British imperialist; Greek island" , "Hordes go to the Greek island" , "Colonial businessman" .)