Let's say you have a vector like so:
(def my-vec [1 2 3 4 5 6])
And you want to extract the first 3 elements and get the remaining elements as a sequence. This can be done as follows:
(let [[x y z & remaining] my-vec]
(println "first:" x ", second:" y "third:" z "rest:" remaining))
;= first: 1 , second: 2 third: 3 rest: (4 5 6)