You should have a detailed job description, contract of employment, disciplinary and grievance policies as a minimum. Ideally your Clerk should have undertaken training appropriate to their role, although this is often not the case. For a Town, I suggest that a professional qualification should be an essential requirement.
Beyond the above, it is for the employer to produce whatever framework they require of their employees, for example an employee handbook covering specific details. There should also be consideration of the extension of some member policies to employees, such as social media etc.