He deals with the customers in a very 'professional' way. = He is very 'professional' in dealing with the customers.
a golf/tennis 'professional' [=a skillful golf/tennis player whose job is to teach other people how to play]
I was impressed by the calm and 'professional' way she handled the crisis.
(..) Lonic bonds. Chapter six. One, two, three makes , and makes . There's your receipt. Just hand this disc to your car-wash professional. Thank you. Come again. He's not coming. He says he quits. I'm gonna run the register. Bogdan, no. We talked about this. I'm short-handed, Walter. (..)2008 TvShow: Breaking Bad Title: Pilot Season: 1 Episode 1