One who is well-versed in any subject; a critical judge of any art, particularly fine arts

One word substitute is Connoisseur.

Veteran: a person who has had long experience in a particular field.
Philistine: a person who is hostile or indifferent to culture and the arts.
Dilettante: a person who cultivates an area of interest, such as the arts, without real commitment or knowledge.
Connoisseur: an expert judge in matters of taste.