Answer:
The unpopular, but certainly easiest solution, would to be blunt about it. Tell them they're being too clingy, and you get your point across more clearly and, though this can be argued, less hurtful than if you were to be passive aggressive about it. Alternatively, instead of using the word "clingy," which may hurt some people's feelings, call it something else like "You're not being very independent." You could also add on, "You would be more attractive if you were more independent," which could lead nicely into the friend working towards becoming a less clingy person by choice and effort.