(def record @{:recipient @{:name "Bob" :age 60} :sender @{:name "Alice" :age 21}}) (put-in record [:sender :age] 26) # @{:recipient @{:name "Bob" :age 60} :sender @{:name "Alice" :age 26}} (put-in record [:recipient] @{:name "Carl"}) # @{:recipient @{:name "Carl"} :sender @{:name "Alice" :age 26}}