The annual review is a two-way process, so it is important that your clerk has the opportunity, in a formal procedure, to talk about their experience of working for the council. It provides an opportunity to discuss the job description and, where necessary, to consider changes. It's also the best opportunity to talk about training, career development etc.
Is the chairman's reluctance to take this forward perhaps a concern about their own capability to manage the process? Training and guidance are available from the local associations.