A vamp is an attractive, dangerously flirtatious woman. A vamp in an old movie might wear tight clothes and bright red lipstick.
The noun vamp is somewhat old fashioned, implying a woman who uses her charisma and beauty to charm men into doing what she wants them to do. You can also use it as a verb, meaning to tease or flirt, especially in a showy and manipulative way. The word came into use in the early 1900's, from vampire. Some experts connect the first use of vamp with the role of "The Vampire" in the 1915 movie "A Fool There Was."