to become stricter or more careful :
Laws on gambling have tightened up recently.
The police are tightening up on under-age drinking.
to become stricter or more careful :
Laws on gambling have tightened up recently.
The police are tightening up on under-age drinking.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005