Measurements made in a laser heated diamond-anvil cell are reported that extend the melting curve of Xe to 80 GPa and 3350 K. The steep lowering of the melting slope (dT/dP) that occurs near 17 GPa and 2750 K results from the hybridization of the 5p-like valence and 5p-like conduction states with the formation of clusters in the liquid having icosahedral short-range order (ISRO).