Exactly this! ... I started learning Clojure but I was too green to build something complex, so my problem was "Where do I get problems to solve with it?" and somehow I stumbled with Project Euler, where many others implement solutions in other esoteric languages as well.
The problems start simple, which is perfect for the "learn the syntax" / "learn the tools" phase.
Then the problems get harder, which is perfect for the "learn the advanced features" / "learn about the community" phase.