This is a clause normally associated with disclosing that a sale is a "Short sale" and that the terms and conditions of the sale are subject to being reviewed and approved by the owner's lender.
Hope this is helpful.
3rd party approval means that the lender or bank for a property that is a short sale has the final decision on accepting the offer. The seller must accept the offer first then that offer is given to the lender to be accepted, rejected, or countered.
Good luck to you!
Prudential Connecticut Realty