If you've met Adelina in Lies of P, you must have already made your way through Rosa Isabelle Street and its myriad hazards to the Estella Opera House. Krat's most beloved singer became trapped on the upper floors after the puppet frenzy began, and to make matters worse, she's got a nasty case of Petrification Disease and doesn't have long left.
Adelina does have a last request, however; a piece of fruit to slake her thirst. If you've yet to find Adelina, the easiest way is to head right up the stairs as you enter the Opera House, then up another level and past the big spider puppet. Once you arrive at the balcony overlooking the burning chandelier, turn left to find Adelina's room. All that said, here's how to help Adelina and find some fruit.
To help Adelina, you'll need to purchase the Bright Red Apple from Polendina at Hotel Krat, but that'll require you to upgrade his item selection first. You can do this by finding the Krat Supply Box, though you might already have located this in St. Frangelico's Cathedral. If not:
Now, take this back to Polendina to expand his stock, purchase the apple from him, and bring it to Adelina in the Estella Opera House. Besides some extra dialogue, nothing will happen straight away. Instead, return after you've defeated the King of Puppets boss to find her body, along with her locket, and the Fascination record you can listen to back at the hotel.