have a tight grip on (someone or something)

have a tight grip on (someone or something)

To maintain strict or tight control over someone; to not allow someone very much independence or autonomy. Ever since George lost most of their life savings in a drunken poker match, his husband has had a tight grip on the family finances. The boss has had a tight grip on her assistant ever since she first hired him.

See also: grip, have, on, tight