The Joy of Clojure
MICHAEL FOGUS, CHRIS HOUSER
MANNING (2011)

It's PDF file (epub, maybe later)

Clojure is a dialect of Lisp, and shares with Lisp the code-as-data philosophy and a powerful macro system. Clojure is predominantly a functional programming language, and features a rich set of immutable, persistent data structures. When mutable state is needed, Clojure offers a software transactional memory system and reactive Agent system that ensure clean, correct, multithreaded designs. (http://clojure.org/)

The authors believe to have written THE book on clojure, I dunno: 
order of used features in examples is educationally a bit messy,
too many forward peeks (or knowledge from other books)
are required, nevertheless: enjoy!