How is “get down to” used?

In The Wolf of Wall Street (2013), one line is: “Let's get down to it. What would you like to know?”

Which movie is “get down to” from?

The clip at the top of this page is from The Wolf of Wall Street (2013).

to begin to do sth; to give serious attention to sth; to go or travel to a place, often somewhere lower

Oxford65% of films
to begin to do sth; to give serious attention to sth
Let's get down to it. What would you like to know?
Editorial35% of films
to go or travel to a place, often somewhere lower

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

Let's get down to it. What would you like to know?

Said in 8 films · #1