I’ve been getting familiar with the Leiningen build tool for Clojure but had trouble connecting to the Clojar and Maven repositories behind a proxy.
I ended up adding my proxy to Maven’s settings.xml and everything worked out.
You can find settings.xml at C:\apache-maven-X.X.X\conf\settings.xml and can edit it according to the conventions described here.
After editing the file run lein deps to download your project dependencies. If still can’t connect to the repository servers you may have to copy the settings.xml file to your .m2 directory at C:\Documents and Settings\username\.m2\settings.xml