To tighten your belt is to spend less because money is short. You will have to tighten your belt this year.
The picture is of eating less and needing the belt pulled in, which is a very old image of hard times. It is said of households and governments alike.
1phrasetighten your beltTo spend less because money is short.
“Tighten your belt for a few months and the debt will clear.”
tighten your belt is a phrase.
Practised in Idioms