1
general::
Set to work, apply oneself with determination, as in All right, we'll buckle down now and study for exams. Originating about 1700 as buckle to, the expression gained currency with the football song "Buckle-Down, Winsocki" (from the Broadway musical comedy Best Foot Forward, 1941). [Mid1800s]
American Heritage Idioms
2
general::
Phrase(s): buckle someone or something down
to attach someone or something down with straps that buckle together. • They stopped to buckle the load down again. • Did you buckle down the kids?, Phrase(s): buckle down (to something)
to settle down to something; to begin to work seriously at something. • If you don’t buckle down to your job, you’ll be fired. • You had better buckle down and get busy.
McGrawhill's American Idioms And Phrasal Verbs