app.clj

(def app-routes
  ;; Echo back the json
  (POST "/lol" req
    (let [json (:body req)  ; wrap-json-body parses the json into a clojure map
          ]
      ;; Now we echo back the json map. wrap-json-response converts our `json`
      ;; clojure map into a string
      {:body json, :status 200})))

(def app
  (-> app-routes
      (handler/site)
      (ring.middleware.json/wrap-json-body)
      (ring.middleware.json/wrap-json-response)))

restclient-command

RestClient.post("http://localhost:3000/lol", 
{:id => "peat", :label => "Peat Bakke", :attributes => [{:for => "attribute_name", :value => 1}, {:for => "something_else", :value => "wee"}]}.to_json, 
:content_type => :json)