Most federations offering a raw division allow a belt.
some will disagree but unlike shirts and suits and knee wraps, a belt is purely supportive and doesn't directly assist the lifter to move the weight. If a belt does help you lift more weight, it's only in an indirect way by providing extra stabilisation - but unlike say knee wraps, the part of the body being given additional support doesn't actually move as part of the lift. It's isometric stabilisation only. This is probably why WPC also recently allowed the use of wrist wraps for their raw division.
On a related note, I have heard reports that many lifters in so called raw divisions are wearing supportive briefs, and these either aren't being declared or are being ignored in the equipment check. For those who aren't aware supportive briefs act like the bottom section of a squat suit, and aren't even allowed in many equipped federations, notably IPF.
