(defn process-scores [user & scores]
  (println "User:" user) (reduce + scores  (filter pos? scores))

can be either

(defn process-scores [user & scores]
  (println "User:" user)
  (reduce + scores)
  (filter pos? scores))

or

(defn process-scores [user & scores]
  (println "User:" user)
  (reduce + scores (filter pos? scores)))