A pretty straightforward clue on the June 1, 2015 game, for $1000 in the Jeopardy! round category Fictional Places:
Dan, the returning champion, was the first to ring in and correctly responded, "What is Oz?" He would go on to win the game again.
And that brings us, for now at least, to the end of Oz in Jeopardy! I'm caught up, and have no more for you right now. There may be a few more before the season wraps up in a few weeks, of course.