Hard to say. If the material has simply yellowed with age, it may not be cleanable because the yellow is a chemical change in the dye. If the color is something that got on it, like cigarette smoke or cooking fumes, then maybe something can be done.
What sort of ceiling material is it? Kind of fuzzy, like a short nap carpet? Vinyl/leatherette?
Is there a place where you can experiment, e.g. an area of ceiling that is inside a cupboard or closet? You need a place to make a trial run with various cleaning agents.
Some folks have had good results with those new stain remover (bleach) pens seen in tv commercials. But if the area is larger, you need something more than a felt tip dispenser.