buckle down

verb

Etymology: From buckle + down.

1. To apply oneself to study, or a task or work; to focus on or take a serious attitude towards something; to put forth the needed effort.

   “If he would buckle down and do his homework, he could be an excellent student.”

   “I confess that the recollection of what this bell could do when it buckled down to it gave me pause as I stood that night at 12.30 p.m. prompt beside the outhouse where it was located.”