Your employer can require you to do work that is broadly related to your role, but not spelled out in your job description. This includes things like helping to clean up your workplace after a natural disaster.
Your employer still has a duty to look after your health and safety if you’re helping to clean up. You have the right to stop work if you believe that you, or anyone else, would be exposed to a serious health and safety risk while cleaning up. You should tell your employer, a health and safety rep, a union rep or Worksafe if you are stopping work because of this risk.