smooth operator

One who is particularly charming and persuasive in one's speech or behavior. Chad is such a smooth operator that he always has women swooning over him whenever we go out. She's a smooth operator who knows how to maneuver her way through the various levels of bureaucracy to get what she wants.

a smooth operator

If you describe someone as a smooth operator, you mean that they are very successful, often by cleverly persuading other people to do what they want. As with many people in the Foreign Office, he is a smooth operator and able to avoid conflict.