A professional office for the personal use of a physician, lawyer, dentist or professional practitioner of a character similar to any of the foregoing, but specifically excluding funeral homes, realty offices, insurance offices and similar practitioners which are provided in the commercial district, provided that the office is located within a residence; and provided, further, that no goods are displayed nor profession identified other than by the display of a sign in accordance with Article XI, Signs. No space is to be rented out of said premises and, further, no more than one agent or one worker are therein employed, and the essential character of the building as a residence is maintained.