New Zealand winger Sitiveni Sivivatu produced a brace of tries as Clermont sealed top spot in the table, with Benson Stanley and Wesley Fofana also touching down.
Toulouse remain favourites to qualify for the play-offs in third place despite the defeat.
Toulon suffered a shock 25-24 defeat to Grenoble at Stade Lesdiguieres to relinquish top spot, while Castres boosted their hopes of a home tie in the play-offs with a 44-17 win over bottom club Mont-de-Marsan.
Perpignan’s faint hopes of reaching the play-offs were ended as they lost 23-15 to Agen, Montpellier lost 32-26 to Bayonne, while Biarritz lost 16-0 to Bordeaux-Begles.
- Sports & Recreation
- Wesley Fofana
- Benson Stanley
- Stade Lesdiguieres