Clear dive, bloody Hell.
From that little clip it also looks as if Xhaka's left foot gets the ball. Did it, or is this an optical illusion?
Whatever...blatant cheating. Did any of the TV pundits call him out for it?
Optical illusion I think. But agree with Sheebo about the spring Zaha puts into it, the only contact was after his little kangaroo leap. 4.15 on the bottom set of highlights here shows it a number of times https://www.ngolos.com/videos/2018-10-28-crystalpalace-arsenal