6 inch approximately pot hole on footpath

This is directly outside my house and has been there for years but it is getting bigger and my open plan garden keeps getting stones kicked into the hole making it worse from residents that cut across my garden. I am very worried that this may cause unstable residents to trip up on the hole when the stones go into it (which will only get worse) and then hold me liable. Please help. It would not take much time or work to put right from a professional thank you.