update-array surely there is a better way

sample.clj

(defn add-athlete [leaderboard division-id athlete]
  (let [divs (:divisions leaderboard) ; [{:id 22 :name "Mens"} {:id 23 "Womens" }]
        indexed-divs (map-indexed vector divs) ;([0 {}] [1 {}])
        div-index (first (first (filter #(= division-id (:id (second %))) indexed-divs)))]

        (update-in leaderboard [:divisions div-index :athletes] #(conj % athlete))))

(def leaderboard {:divisions [{:id 22 :name "Mens" :athletes []} {:id 23 "Womens" :athletes []}]})

(add-athlete leaderboard 22 "Dru Sellers")

;{:divisions [{:id 22 :name "Mens" :athletes ["Dru Sellers"]} {:id 23 "Womens" :athletes []}]}