leave it to

leave (something) to (one) (to do something)

1. You can depend on one (to accomplish a particular task). A: "I need to find someone who can fix my back fence." B: "Leave it to me! I've already got all the tools and materials I'll need." I'll leave setting up the internet and stuff to Janet—she's better with those sorts of things.
2. It is very typical of one (to do something or behave in a particular way). Leave it to Brian to screw up the one thing we asked him to do. A: "My computer isn't connecting to the internet." B: "Ugh, leave it to the IT department. They're always changing the login passwords with out telling us!"
See also: leave

leave it to someone

to depend on someone to behave in a certain way. Leave it to Harry to mess things up. She did it wrong again. Leave it to Janet! Jane: Will you do this as soon as possible? Mary: Leave it to me.
See also: leave