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.
(..) Oh, hello, Ted. Oh, if you're worried about my husband, it's fine. He's no bigger than a Cub Scout. You could take him, and you could certainly take me. This has been pleasant and professional. Good luck in the coming business year. - Hey, you guys are sticking stuff on Gob's suit? - Shh. (..)2004 TvShow: Arrested Development Title: Afternoon Delight Season: 2 Episode 6