Denote properly an unused parameter

Author: bbatsov

clojure-mode.el

@@ -543,7 +543,7 @@ replacement for `cljr-expand-let`."
   ;; `electric-layout-post-self-insert-function' prevents indentation in strings
   ;; and comments, force indentation in docstrings:
   (add-hook 'electric-indent-functions
-            (lambda (char) (if (clojure-in-docstring-p) 'do-indent))))
+            (lambda (_char) (if (clojure-in-docstring-p) 'do-indent))))
 
 (defcustom clojure-verify-major-mode t
   "If non-nil, warn when activating the wrong `major-mode'."