Verb
keep a tight rein on (third-person singular simple present keeps a tight rein on, present participle keeping a tight rein on, simple past and past participle kept a tight rein on)
To exercise strict control over; keep in check.
One of the persons expected to keep a tight rein on the military, from a spiritual standpoint, is the military chaplain. Source: Internet
“We’re owned and operated by the Australian wool industry, so because our owners are also our biggest clients, they keep a tight rein on us,” he said. Source: Internet