I was interested in the same question (how big is a simple Scheme in Clojure?), and ended up working on one for the heck of it. It's a little under 500 lines of Clojure, and it has a very small number of primitives at this point.

I tell myself some day I'll go back and build a read layer so I can have macros.

https://github.com/CJOlsen/fez/blob/master/src/fez/core.clj