Because Clojure's for macro allows you to "walk" over multiple sequences in a nested fashion, it is excellent for transforming all sorts of sequences. If you don't want a sequence as your final output (say you want a map), you are often still best-off using for, because you can produce a sequence and feed it into a map, for example.

For this problem, your goal is to "flatten" a map of hashmaps. Each key in your output map should be the "path"¹ that you would have to take in the original map to get to a value, so for example {1 {2 3}} should result in {[1 2] 3}. You only need to flatten one level of maps: if one of the values is a map, just leave it alone.

¹That is, (get-in original [k1 k2]) should be the same as (get result [k1 k2]).

(ns live.test
  (:require [cljs.test :refer-macros [deftest is run-tests]]))
  
(defn tnt [m]
  (into {} (for [[k v] m [k2 v2] v] [[k k2] v2])))

(deftest tnt-test
  (is (= (tnt '{a {p 1, q 2}
          b {m 3, n 4}})
    '{[a p] 1, [a q] 2
     [b m] 3, [b n] 4}))
  (is (= (tnt '{[1] {a b c d}
         [2] {q r s t u v w x}})
   '{[[1] a] b, [[1] c] d,
     [[2] q] r, [[2] s] t,
     [[2] u] v, [[2] w] x}))
  (is (= (tnt '{m {1 [a b c] 3 nil}})
   '{[m 1] [a b c], [m 3] nil})))
  
(run-tests)