The Year of the Griffin by Diana Wynne Jones
The Wizards' University is short of money. Nothing comes in from tourists any more since Mr Chesney's offworld tours have stopped. High Chancellor Querida has left Wizard Derk and his family to run the work and handsome Wizard Corkoran to run the University. Corkoran is really only interested in being the first man to walk on the moon, but he does send begging letters to the students' parents. But Wizard Derk's daughter Elda turns out to be a large golden griffin, King Luther's son is penniless, the Emperor's sister has been disowned by the senate and the dwarf, far from owning a hoard of treasure, turns out to be a runaway slave. And then the first answer arrives: in the form of assassins ...The situation is definitely out of control.