I've always thought that oats could be a problem with gluten, too.
I've made a walnut crust many times for cheesecake, and it is delicious. I just ground walnut pieces up in my aged blender, and added sugar and butter. It is an Atkins recipe - I'm sure that there are many online. You could probably use other nuts, too. Almonds are hard and don't grind as easily, but almond flour is available.