The most simple thing you can do is dig down, place the workbench, raise ground a bit (but not to much), fix height with pickaxe and then place stone/wood over workbench to hide it.

But a lazy way (and also doesnt look horrible), is to raise ground a bit so mobs cant reach it, place a workbench on top and some wood araund it and make it look like a beehive or something else.