Sure but you dont just drop them in..
In a small amt. of water boil the bananas until it blows up alot , Strain and add the "soup" to the carboy. You should do this before clearing as this will cloud it up some.
Boiling sounds like a good idea. Someone else told me to smash them and put them in a bag and drop them in the fermentation bucket. I think I'll try it since the VR wines are made with less juice.