Whilst there's a comment about "other staff" in this post, it's not clear if those "other staff" are able to undertake the work of the clerk so I wouldn't necessarily assume there is someone else to provide holiday cover. It is very common for clerks, not just those who work alone, to find themselves struggling to catch up after any time off. Additional hours seem almost inevitable, It's also difficult to say what's excessive or not as all councils are different, have different responsibilities and services and differing demands on the clerk's time. Paying for any additional hours is still going to be less expensive than employing a locum to cover the clerk's absence in most cases.