1934, Rex Stout, , 1992 edition, ISBN 0553278193, page 97:I have learned that there is a person attached to a golf club called a professional. Find out who fills that post at the Green Meadow Club; ... invite the professional, urgently, to dine with us this evening.
Full definition of professional
Adjective
professional
Of, pertaining to, or in accordance with the (usually high) standards of a profession.
1907, w, The Younger Set Chapter 2/1, His forefathers had been, as a rule, professional men—physicians and lawyers ; his grandfather died under the walls of Chapultepec Castle while twisting a tourniquet for a cursing dragoon ; an uncle remained indefinitely at Malvern Hill ; … .