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.
(..) ...until you are dead... ...in accordance with state law. God have mercy on your soul. Roll on two. That's that. Very good. Very professional. Let's do it again. You got all the words right. It sounded just fine. - Thank you. - Yep. (..)1999 The Green Mile