If you presume that an employee may leave after receiving their full salary, it is indeed a matter of concern for every establishment, and they must take action to prevent it. You cannot impose a clause as it would go against the laws and regulations. Instead, you can issue a letter stating that due to the pandemic situation, some of your payments are being deferred, as is the case for all other employees in our establishment. Your outstanding balance will be settled at a later date when the situation improves. Ensure that you continue to pay the basic withholding and other components without any interruption.