Ludwig van Beethoven's Piano Sonata No.8 in C minor is known as the "Sonata Pathétique". The slow movement of this sonata is the most famous part and, because of its lyrical melody and steady accompaniment, it is readily arranged for other instrument combinations. This version has been arranged by Artur Akshelyan for B-flat Clarinet and Piano, and you can download the piano and clarinet sheet music parts (and midi and mp3 versions) using the links in the left-hand menu.
If you are considering more music for Clarinet and Piano, we suggest the book "Concert Repertoire for Clarinet" which is a varied selection of mostly classical music arranged for this combination. It is available from these links at www.musicroom.com and at www.sheetmusicplus.com.