The structure of xenon fluoride is a capped octahedron. The lone pair is stereochemically active, i.e. it will rotate about.
The dipole moments of the axial fluorides will get cancelled, and so will those of the four equatorial fluorides will also cancel each other. Thus, overall, the molecule should be nonpolar.
But what effect will the stereochemically active lone pair have on the polarity? Will the polarity keep on changing?