Exercism assignment for word-count in Clojure
I would format it like this:

(ns phrase
  (:require [clojure.string :as s]))

(defn word-array [phrase]
  (s/split (s/lower-case phrase) #"\W+"))

(defn word-count [phrase]
  (frequencies (word-array phrase)))


Notice that I included the require statement as part of the ns definition. 

Whether or not you use threading macros (-&gt;, -&gt;&gt;) is generally a matter of personal preference, and there's nothing wrong with using them here, but I think in this case since you're only using 2 functions, I find the above easier to read. You might also consider using comp:

(def word-array (comp #(s/split % #"\W+") s/lower-case)
(def word-count (comp frequencies word-array))