I was trying to make some cupcakes for a church function tonight and i think my clear vanilla has gone bad and now my butter cream taste a little bitter...is there anyway that i can correct this without making a whole new batch of buttercream? I will have to go to the store and buy new and im not sure I have time for that....

I'm not an expert on food safety or anything, but I personally would buy more and make a new batch. I basically follow the "when in doubt, throw it out" rule.

As I said, I'm no expert, though. So this will at least give you a bump so others will see it