The council by ordinance may combine the offices of clerk and treasurer in the office of clerk-treasurer and thereafter the duties of the treasurer as prescribed by this charter and law shall be performed by the clerk-treasurer. The office of clerk and treasurer may be re-established by ordinance. If the offices of clerk and treasurer are combined, the council shall provide for an annual audit of the city’s financial affairs by the public examiner or a public accountant in accordance with minimum procedures prescribed by the public examiner.