Defiant child


Help! My son is 4 and 1/2 years old and just started preschool. His teacher says he's refusing to do class work. Saying no and not listening to instructions.. he also don't listen to my parents, me or his daddy. He is very smart but bad behavior. Idk what to do. I talked to his pediatrician they dont give medicine til 6. I'm thinking about doing play therapy consuling with him with a social worker/ psychiatrist. Any suggestions.?