Hopefully above clause ( textbook at that) was termed in the buyers initial offer/contract...( which doesn't sound like the case)
IF it was then then there ya go = problem solved
However, recognize that it's almost impossible to force someone to buy a home . . . even if you have a valid contract. (You might be able to retain whatever earnest money deposit they put on your home. Your lawyer can advise you on that.)
They've obviously gotten buyer's remorse. What you and your agent have to try to do is reassure them that your house is a good value . . . even better since the appraisal resulted in a lowered price you're willing to sell for. Your agent (and the buyers' agent) have to persuade the buyers that they won't find another home with the same qualities, in the same (repaired/improved) condition. Yours is the best buy. If they're serious about buying at all, then your house is the top choice for them. That's the argument that has to be made.
One other point: Hopefully your offer on the new house contained a financing contingency. If so, and your sale falls through, then obviously you won't be able to get financing on the new home. That should protect you and your earnest money deposit. If the sale still falls through, you'll be out the cost of the inspection on the new home. But--possibly--you'll get your earnest money back from your hoped-for home purchase, you'll be able to retain the earnest money deposit from the bailed buyers, and you've done repairs that'll make your present house more liveable . . . and easier to sell if/when you put it back on the market.
Again: Check with your Realtor and with a lawyer.
Hope that helps.
I am NOT an attorney. Good luck.