Cleff is a music sparrowman who appears in Trill Changes Her Tune. He is the conductor of the Oceanside Symphony.
During the course of the story, he is established as a very stiff, stoic figure who is very sure of himself. He believes in keeping things the way they've always been, at the expense of innovation, and rebuffs Trill when she suggests changing the Symphony to feature many new instruments.
Despite his antagonistic role, he is not unkind- simply stubborn and unwilling. He arranges to have Trill's important panpipes fixed, and rescues her from a porcupine's quills, though occasionally voices his displeasure at Trill not following the rules.
By the story's end, he sees the beauty in what Trill was doing. Trill, too, understands Cleff's desire for caution. Thus, both come to an understanding, and work to improve the music-talents' performances.