From Longman Dictionary of Contemporary Englishlet somebody loose on somethinglet somebody loose on somethingDEAL WITHto allow someone to deal with something in the way they want to, when you think they will make mistakes or do something wrong Whatever you do, don’t let Derek loose on the garden. → loose
Examples from the Corpus
let somebody loose on something• Who was feeding him or even letting him loose on occasions?• We let the Pacer loose on two testers - one fast, one slow.• He seemed to have forgotten about only letting me loose on water. 