Old hand

Near-synonyms: insider, initiate; habitué

My tax advisor is an old hand at dealing with auditors.

The media, needless to say, are very pro-Bloomberg. He’s an old hand at stroking reporters and television executives, and few of them have raised the fact that it was Rudy who inherited a lawless city with crime out of control and over eight years, via his ‘broken windows’ theory, turned Gotham into the safest big city on the planet.