If it's this particular piece that story_teller's looking for, it is called Clog Dance, and it's from a ballet, not an opera. The original composer/arranger of the music (most of it consists of adapted French traditional tunes) is unknown. Hertel's adaptation of the music (it's had several incarnations over the years) was used by John Lanchbery to create the Clog Dance tune for Frederick Ashton's 1960 production of the ballet. It's Ashton's production that most of us are familiar with.