Grammar fix
knuckle down
make yourself work
To force yourself to work hard and seriously, especially on something difficult or important.
phrasal verb
How oftenNow and then
LevelB2
Used inSpeech & writing
Hear it in context
Notice where the phrase sounds natural.
I’m going to have to knuckle down if I want to finish this assignment tonight.
I had to knuckle down during my final year because the workload was much heavier than I expected.
Fix the pattern
One small grammar move makes it sound right.
Not: I need to knuckle under and finish my essay.
Say: I need to knuckle down and finish my essay.
'Knuckle under' means give in to someone's authority; 'knuckle down' means start working hard.
Don't confuse it
Other ways to say it
Start working seriously and properly
How determinedFocusedVery determined
get down toStarting serious work after distraction or delay.
knuckle downYou're here · A bit more British: make yourself work hard, e.g. for exams.
buckle downA bit more American: start working hard and seriously.