Australian international hooker Nathan Charles has been signed by Clermont as medical cover, the Top 14 side said on Wednesday.
The 27-year-old, an ambassador for cystic fibrosis, from which he suffers, will start training with the club on Thursday.
He has been signed as cover for compatriot John Ulugia, who damaged knee ligaments against Racing 92 on September 10 and is expected to be out for three months.
"(Charles's) profile corresponds perfectly with the style of play we hope to implement with both solid guarantees in the fundamentals and great mobility," said Clermont head coach Franck Azema on the club's website.
Charles, believed to be the only cystic fibrosis sufferer in the world to be competing professionally in a contact sport, joins from Western Force in his homeland.
He has four Wallaby caps and made his debut in a 6-0 win over France in June 2014.
Cystic fibrosis is a genetic disorder that primarily affects the lungs, causing infections.
Life expectancy in sufferers is considerably shortened, although in the developed world it is typically 42 to 50 years according to some experts.