The word claret is an anglicized version of the French term clairet – which is a dark rose wine typical to Bordeaux. The term has evolved since its first use in Britain to refer to dry, dark red Bordeaux wines.
With regards to wine, specifically, it can be used on any wine modeled after the Bordeaux blend, from anywhere in the world. New world wineries and estates use “claret” on their labels to refer to red wines made in the same styles and with the grapes typically used in a Bordeaux Blend.
Due to the prestigious origins of the word – the upper class and high society of Britain – many producers include “claret” on the labels of generic red wines from Bordeaux in an attempt to make them more appealing to consumers. In fact, the term is not used in France, producers will only put the term on the labels of bottles they intend to export.