Idris of "Luther" (4)
I believe the answer is:
elba
'idris of luther' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elba that I've seen before include "Napoleon's Mediterranean exile island" , "Island off Italy" , "Exile isle for Napoleon" , "place for Napoleon" , "Island of imperial exile" .)