This character is, quite simply, a character whose defining trait is being well-dressed and extremely interested in fashion.
The Fashionista is often a woman, save for instances of The Dandy, or a Camp Gay guy (whether or not he is a fashion designer). The Fashionista will invariably love to shop, read Fashion Magazines, and watch (or be involved in, if she is a model or a designer) Fashion [...] [tvtropes.org]