grep-in.el

(defun grep-in (project-root)
  (interactive (list (read-directory-name "Project Root: " 
                                          (locate-dominating-file 
                                            default-directory
                                            "project.clj"))))
  (er/mark-clj-word)
  (grep (concat "grep -nH -e " 
                (buffer-substring-no-properties (region-beginning) (region-end))
                " -R " project-root)))

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