How can I make granola that clumps?
Contrary to what some people seem to be saying, fat will reduce the clumping effect, same way it does in almost every other baking recipe.  The clumping behaviour comes mainly from sugar (syrup) and protein content.

In other baking recipes, gluten does a lot of the "clumping"; oats are naturally gluten-free, but the instant oats you buy are probably processed in the same plants as other wheat products and are therefore contaminated with gluten, which may explain why they clump more in your granola.

So I'd recommend any or all of the following for you:


If your recipe contains any oil or other fat, reduce or eliminate it; the primary purpose of that ingredient is to reduce the natural clumping.
Increase the quantity of flour or starch.  More gluten means more clumping and a generally chewier texture.
Increase the quantity of sugar or honey.  A denser syrup is going to be "stickier" and therefore clump more.  Note that this can interfere with gluten development so you might want to do this in addition to increasing the starch.
Substitute the oil/fat with applesauce.  This is a common substitution in low-fat baking, although its applications are limited.  It's perfect in your case though, because it not only lowers the fat content, it also adds natural sugar and pectin, the latter of which is a gelling agent (albeit a weak one).
Add an egg white.  That's very good at binding ingredients and is common in granola recipes.
As a last resort, use an actual gelling agent such as pectin crystals, gelatin, or agar.  You shouldn't have to do this, but if you have a recipe you really adore except for its texture, then that's the best way to change the texture without altering the flavour at all.