If it's based on another style, enter it as a fruit beer. Fruit beers should have the characteristics of the base style. Otherwise, enter it as experimental.
Fruit, Make sure to list the base style though. such as an Ale.. I entered in the fruit category and got marks for not having a "style" to judge against. They were'nt neccessarily bad marks, they just couldn't judge it as well without something to go by. Basically I made a Cranberry ale, but didn't mention the "ale" part. just put cranberry as a Fruit Beer.