Complex sentence: Mahut, who had settled in Fontainebleau during his childhood, started his football career at that town's local club Racing Club de Fontainebleau, which was in Division 2 from 1970 to 1978.
Split into simpler sentences: Mahut, who had settled in Fontainebleau during his childhood, started his football career at that town's local club-Racing Club de Fontainebleau. It was in Division 2 from 1970 to 1978.