expression, ichidan verb
tighten the purse strings; tighten one's belt
Idiomatic expression meaning to become more frugal or to control spending, literally 'tighten the strings of one's wallet'.
収入が減ったので、財布の紐を締めなければならない。
Since my income decreased, I have to tighten my purse strings.
彼は無駄
He spends too much, so his wife is keeping a tight rein on the finances.