buckle down
US /ˈbʌk.əl daʊn/
UK /ˈbʌk.əl daʊn/

1.
se dedicar, se empenhar
to start working seriously and with determination
:
•
It's time to buckle down and finish this project.
É hora de se dedicar e terminar este projeto.
•
If you want to pass the exam, you need to buckle down and study.
Se você quer passar no exame, precisa se dedicar e estudar.