If the tenant has not complied with this provision of the lease agreement you don’t have much recourse. The Residential Tenancies Act does not include any provision requiring tenants to obtain insurance and does not provide any remedy for landlords, it is not grounds for eviction. The purpose of having this clause in your lease is to clarify that it’s the tenant’s responsibility to obtain insurance and it protects you against certain claims the tenant might have if a problem arises.