instruct
verb [ T ]
uk/ɪnˈstrʌkt/ usto order or tell someone to do something, especially in a formal way:
instruct sb to do sth They were instructed to remove the vehicles from the site immediately as they were causing an obstruction.
to teach someone about something or how to do something:
instruct sb on/in sth Employees will be instructed on the use of the new invoicing system that is being introduced next month.
LAW UK
to employ a lawyer to deal with a legal case, and to tell them what you want them to do:
We'll instruct our lawyer to draw up an agreement.