"Odyssey" setting
I believe the answer is:
'odyssey setting' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ithaca that I've seen before include "Odysseus's home" , "Greek island sought by Ulysses" , "Birthplace of Odysseus" , "part of NY" , "Ionian island, home of Ulysses" .)