In 1998, Clichy joined AS Tournefeuille and began attending secondary at the Collège Leonardo da Vinci. During his stint at Tournefeuille, he was selected to attend the Pôle Espoirs de Castelmaurou, a regional academy located in the Midi-Pyrénées region that trained players similarly to the Clairefontaine academy in Île-de-France. Clichy spent three years at the center training there during the weekdays and playing with Tournefeuille on the weekends. In 2000, after developing at both Tournefeuille and Castelmaurou, Clichy was linked to a host of professional clubs, including Auxerre, Bordeaux, and Toulouse who were seeking to obtain his services. The young player ultimately decided to move to the Provence-Alpes-Côte d'Azur region to play for professional club Cannes.