First, take a look at Try Clojure; this gives you a Clojure prompt ('REPL') in your browser, and a brief tutorial. Then:
- For a detailed introduction to Clojure, Mark Volkmann's Tutorial
- To practice, 4Clojure: Fill-in-the-blank exercises from beginning to advanced. Click on one of the 'title' links to do a problem
- To get Clojure up and running on your machine, Clooj: A simple IDE/editor with a REPL
- Once you're comfortable with Clooj, install Leiningen and read the tutorial.
You'll need Lein to build programs and run them at the command line, and also to use Clojure libraries.
- If you need a more powerful development environment (with a learning curve to match), try Emacs, the choice of many experienced Clojurians.
If you want a standard IDE, there are plugins for Eclipse, Netbeans, and IntelliJ, among others.
- debugging with JSwat
- Statistics and graphing: Incanter
- API documentation organized by functionality
- For a complete categorized listing of Clojure tools, check here