Clausen started in the Sprint in Drammen for the first time in the World Cup in March 2008 and finished his debut in 37th place. In his second outing a year later in Trondheim - also in the sprint - he achieved World Cup points for the first time with 22nd place. Clausen achieved his first top 15 result in the World Cup in February 2011 in the Drammen sprint with 13th place. He achieved this three more times in the sprint: 11th in Drammen in March 2012, 13th in Canmore in December 2012 and Rank 10 in February 2013 in Davos . Clausen also came third in the Norwegian sprint championships in 2012 and won one sprint race in the 2009 and 2011 Scandinavian Cup .