Island boasting a vehicle, out of bounds (6)

I believe the answer is:

ithaca

I'm a little stuck... Click here to teach me more about this clue!

'island' is the definition.
(I know that Ithaca is a island)

I cannot understand how the remainder of the clue works.

(Other definitions for ithaca that I've seen before include "Where Ulysses was produced" , "Greek island, legendary home of Odysseus" , "Greek island sought by Odysseus" , "Ionian island, home of Ulysses" , "Birthplace of Odysseus" .)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app