Do not use the word deposit anywhere in your conversations or in your paperwork. Use Non-refundable HOLDING FEE instead. By definition a deposit is refundable and a fee is not. The LPA rental binder document does not address the possibility of a refund becuase they may change their mind or back out. There may be a refund only if you the LL decide to. If you keep the place off the market for 35 days for this person you are entitled to the entire holding fee, with absolutely no refund. Non-refundable holding fee, and make it perfectly clear to this person.
Please tell me where the definition of a deposit is refundable. Have you ever given a deposit for a hotel room or an airline ticket/ They usually have very specific terms to be refundable otherwise you lose.