Complex sentence: They guess that he wished for a Harley-Davidson and persuade him to enter a competition to win ohe fete where the winner of the motorcycle is to be announced, they hear the thoughts of an unhappy mime who wishes (they think) for fame.
Split into simpler sentences: They guess that he wished for a Harley-Davidson and persuade him to enter a competition to win one. At the fete where the winner of the motorcycle is to be announced, they hear the thoughts of an unhappy mime who wishes (they think) for fame.