to keep a tight rein on

Meaning

1. to keep a tight rein on sb / sth

   to control sb / sth carefully or strictly

From the same entry

• run a tight ship
• a tight spot
• sit tight
• sleep tight
• tie in knots
• tie one on
• tie the knot
• apron strings
• bind hand and foot
• have your hands tied
• tie down
• tie in