a customer of your branch approaches you for an advance against fixed deposit of 50000 of another bank issued in his favor. What action would take in this case?

As a rule, no advance is to be allowed against a fixed deposit receipt issued by another bank become of obvious legal complications. A fixed deposit receipt is not transferable. So, if such advance is to be made then a deed of assignment is to be executed by the depositor in favors of the bank from whom he is going to borrow money and, that deed will attract ad valorem with the bank concerned to the effect.