grep-in-project.el

(defun grep-in-project ()
  (interactive)
  (er/mark-clj-word)
  (let* ((project-root (locate-dominating-file 
                         (file-name-directory (buffer-file-name)) "project.clj")))
    (if project-root
        (grep (concat "grep -nH -e " 
                      (buffer-substring-no-properties (region-beginning) (region-end)) 
                      " -R " project-root))
      (message (concat "no project.clj found at or below " (buffer-file-name))))))

(global-set-key (kbd "C-c g") 'grep-in-project)