(add-hook 'lisp-mode-hook
  (lambda ()
    (font-lock-add-keywords nil
      '(("(\\(\\defklass\\)\\s \\(\\(?:\\s_\\|\\sw\\)+\\)"
         (1 font-lock-keyword-face)
         (2 font-lock-type-face))))))

(put 'defklass 'common-lisp-indent-function
     (get 'defclass 'common-lisp-indent-function))