To use clojure-mode in Emacs, add the following lines to your ~/.emacs:

  (autoload 'clojure-mode "clojure-mode" "A mode for clojure lisp" t)
  (add-to-list 'auto-mode-alist '("\\.clj$" . clojure-mode))

In addition, if you are also using paredit, you may wish to make it
more Clojure aware:

  (autoload 'paredit-mode "paredit" "Parenthesis editing minor mode" t)
  (eval-after-load "clojure-mode"
    '(progn
       (defun clojure-paredit-hook () (paredit-mode +1))
       (add-hook 'clojure-mode-hook 'clojure-paredit-hook)

       (define-key clojure-mode-map "{" 'paredit-open-brace)
       (define-key clojure-mode-map "}" 'paredit-close-brace)))