Fig. to watch and control someone or something diligently. (Alludes to controlling a horse by a tight grip on the reins.) The office manager kept a tight rein on the staff.Mary keeps a close rein on her children.
to control someone or something carefully Clarke has consistently pointed to the need to keep a tight rein on government finances.He kept a tight rein on his daughter.
to have a lot of control over someone or something He made ends meet by keeping a tight rein on his budget.Our parents always kept us on a pretty tight rein.