Is it a quilt top or finished quilt? If it is a quilt top I would put a drop of clear dish soap on the spot, rub it in a bit and drip hot water from my tea kettle through it. Try in on a scrap of white fabric first to see how it goes. You could also try a tide spot cleaner pen on the spot but again try on a scrap first.
If it is a finished quilt, I would make sure the backing fabric is colour fast before doing anything. You don't want a colour bleed to come to the front. Also be careful of whatever you try on the front doesn't bleach the backing.