Good way to get a tag a string and a map

tag_map.clj

(ns tag-map.clj
  (:gen-class))

(defn tag
  [word]
  (str "`" word "`"))

(def line-str "This is a test to see if this works.  It's a cool dog test.  One must work hard to get the right answer.")

(def keywords
  {"right" (tag "right")
   "test" (tag "test")
   "answer" (tag "answer")})

(defn upper
  [line]
  (clojure.string/upper-case line))

(defn upper-map [m f]
  (into {} (for [[k v] m] [(f k) (f v)])))

(defn replace-map
  "given an input string and a hash-map, returns a new string with all
  keys in map found in input replaced with the value of the key"
  [s1 m1]
  (let [s (upper s1)
        m (upper-map m1 clojure.string/upper-case)]
    (clojure.string/replace s (re-pattern (apply str (interpose "|" (map #(java.util.regex.Pattern/quote %) (keys m))))) m)))

(defn -main
  [& args]
  (println (replace-map line-str keywords)))