After spending his first years as a senior with the reserves, he was loaned to Toulouse FC with which he first appeared in Ligue 1, making his debut in the competition on 14 August 2004 in a 4–1 away win against RC Strasbourg.

Returned to L'OL for the 2005–06 season, Clerc went on to become and important first-team member as the club won three national championships in a row, contributing with 62 league appearances combined in that timeframe.

[3] In the fall of 2010, free agent Clerc joined OGC Nice also in the top division after convincing manager Eric Roy his knee injury problems were a thing of the past.

[8][9] Clerc earned his first cap for France on 11 October 2006, in a 5–0 win over Faroe Islands for the UEFA Euro 2008 qualifiers.

[10] He was selected by coach Raymond Domenech for the finals in Austria and Switzerland, replacing longtime incumbent Willy Sagnol for the last and decisive group stage clash against Italy, which ended in a 2–0 loss and exit.