knuckle down to

Often, it’s for a payday, and even when the impulse isn’t merely financial, performers, bands or comedy teams — they are the same in so many ways — might remain content to recycle the old hits rather than knuckle down to do new creative work.

But as the United Nations conference enters its second week and negotiators from 197 countries knuckle down to finalize a new agreement to tackle global warming, attendees were sharply divided over how much progress is being made.

Speaking to the BBC on Wednesday, Irish Taoiseach Micheál Martin said the UK has to "knuckle down" to get a trade deal with the EU by the end of the year, when the Brexit transition period ends.

The UK has to "knuckle down" to get a post-Brexit trade deal with the EU, the Irish Taoiseach Micheál Martin has said.

TJ’s parents have felt fear, too, in the wake of Gene’s death — but they have decided to knuckle down to work.