She's the daughter of the devil. Her problem is that she's the only child of the devil and the vampire. Clare doesn't want to inherit the throne for the devil. Her hobby is reading books and wanting to adventure instead of locked up.
Clare wants to break free of her fate of being enthrone as the next devil. Unlike the demons under her father's reign she didn't terrorize humans or attack them.
She wanted to live peacefully with the humans and going out to the world.
Instead she is locked up in the castle waiting to be enthroned. She is bored of being locked inside the castle by her father. On her coronation things don't go as expected as her father expects.