Clever Clare is thought to be the smartest girl in Henry's class. She's thought to be a tell-tale which was shown in Horrid Henry's New Teacher.
In the TV series she has been moved from Henry's class to Peter's class, as shown in Horrid Henry: Nothing But The Truth, and is taller than her classmates. It is likely that she has de-aged due to the fact she was in Henry's class in the books. Her Arch Enemy is Brainy Brian.