The clerk's wage is personal data and they have the option, but are not obliged, to withhold it from the public. The council can't withhold disclosure of the total council salary expenditure, so if the clerk is the sole employee, their salary should be revealed from that. I think you need to be specific about a business account. Is it an account with a specific supplier, or is it a corporate bank account? The clerk should not have been using their personal bank account for council financial transactions.