Spilling balsamic vinegar on a piece of clothing won't ruin the item if you remove the stain quickly. Laundry soap and white distilled vinegar will remove the stain. While it's possible the stain will disappear during a normal washing, it's safer to treat it beforehand. This way you don't have to worry about the stain setting in during the wash, or having to rewash the item several times after you treat it.
Hold the piece of clothing under running cold water. Hold it so that the water runs only through the stain and not the rest of the fabric. This prevents the stain from spreading.
Pour the liquid laundry soap onto the stain. Work the soap into the stain with your fingers.
Add the white distilled vinegar. Let the piece of clothing sit for five minutes.
Rinse the stain with cold water.
Wash the piece of clothing.