"Cliff Hanger and the Marching Band" is a book in The Adventures of Cliff Hanger series by Livingston Dangerously.
Atop his cliff, Cliff Hanger hears a marching band looking for new members. When he reaches into he backpack to extract his survival manual, he learns that in order to get in, he must show the leader his tuba skills. He does, and the leader likes it. However, the leader tells him that there are too many tuba players in the band as is. Cliff recommends they give him a hand, which they do, by clapping. Cliff plays his theme song on the tuba before tossing it away.