Assume I have src/cljc/a/b/c.cljc. If I navigate in dired to src/cljc/a/b and then C-x C-f new.cljc then a new buffer is created (ns cljc.a.b.new).
Namespaces are setup correctly so src/cljc is a source path according to project.clj.
Libraries are Clojure 1.7.0 and snapshot cider.