One word for...

A maven? An authority?

Anonymous For example, a politician in the field of politics

Politico [?]

thanks. But I wanted a word with a negative shade...like someone who is cunning

Thanks, Philip. A politico would be very specific, I was looking for something more discrete. Frankly, I don't know if a word like that exists in english...I am translating a book which is in my native language to english and I can't find a single word meeting these requirements. Basically it's about a person who is 'well groomed' or 'seasoned' in a cunning way

Hi Anonymous,

Politician: One versed or experienced in the science of government
Statesman: one devoted to politics.
Pseudo-politician: a false politician.

Regards,
Sri

It could be a connoisseur or a professional you are looking for.