The home side registered their first win of the Heineken Cup campaign but not before seeing a commanding 22-3 halftime lead overturned by the French side who rattled three converted tries inside nine second half minutes to lead 24.22. But a 64th-minute penalty from Dan Biggar put the Ospreys back in the lead and they held on for the vital win.
Ospreys attacked from the opening whistle to set up James Hook who knocked over a drop goal in the second minute. The home side went further ahead seven minutes later when Irish centre Tommy Bowe collected a neat chip from Nikki Walker.
Clermont hit back with a drop goal by Brock James but the Frenchmen were reduced to 14 men when second row Thabault Privat was shown a yellow card for a trip on Shane Williams.
Ryan Jones made the extra man count when he pounced from short range. With Biggar adding the extras the home side had jumped out to a 15-3 lead on 28 minutes. Jerry Colins was then sent to the sin-bin – not for the first time this season – for an illegal challenge on James.
Wales scrum half Mike Phillips then limped off with an injury to his right ankle on 33 minutes.
Former Scarlet Barry Davies then scored with the last move of the half with Biggar and Bowe heavily involved in the lead-up.
The Ospreys may have enjoyed the first half, but in the second period Clermont Auvergne burst into life to get right back in the match.
The second half was only two minutes old when winger Benoit Baby caught the home defence napping. Replacement prop Domingo then squeezed over for the second try and made the break for flanker Alexandre Lapandry to go over three minutes later.
Ospreys went back into the lead on 64 minutes when Biggar banged over a long range effort. The French side had a try disallowed when wing Napolini Nalaga was forced into touch before getting the ball down in the corner.
James had a chance to put the French side back in front on 74 minutes but his shot struck the left upright. And as much as they tried, that was the closest they would come to taking away the spoils.
