"A Mexican Serenade" by Scott Joplin. Clarinet solo with piano accompaniment. This beautiful, haunting tango, the only one that Scott Joplin composed, was made famous when used in the sound track of "The Sting".
Difficulty guide: 6
Difficulty level, roughly compared to ABRSM exam grades. 0 is total beginner, 9 is advanced (beyond grade 8).