It's a fun clue. I'd think many who follow Broadway might know this. First those who know the nuances of the career of someone like Peters. This show was recently featured in Playbill's photo tribute to Bernadette Peters birthday. And two, those who discovered that both Nine and Sweet Charity were based on Fellini flims and possibly took a deeper dive into Feillini's world. It was also on my radar because Woody Allen has made his own version of several Fellini films. La Strada being the inspiraiton for Sweet and Lowdown. (Amarcord inspriing his Radio Days and 81/2 inspriring his Stardust Memories).
Now, don't ask me about the all the tons of clues I would never get right in other categories :-)