Gravy

[Cheetah Designs]

So the way I make my gravy is by adding the liquid that comes out of the beef joint after its cooked/rested to Bisto and then add the water from an vegetables cooking if it needs to be thinner/more volume.

However because of all the fat that has obviously come out the beef, I'm finding that the gravy is splitting and you end up with a layer of clear greese/fat on top. How can I prevent this from happening?