To remove rust from clothes, you can cover the stain with cream of tartar (gathering up the edges of the item to keep the powder on the spot), then dip the spot in hot water. Let stand 5 minutes, then wash as usual. If the item is white, you could also apply lemon juice to the stain, rub with salt, and let it bleach in the sun.
There are also several commercial products available that are designed to remove rust stains, such as Zud or Whink. If the item is white, you could also apply lemon juice to the stain, rub with salt, and let it bleach in the sun.