I agree entirely with your starting point. What's more, the council should reflect the interests of the citizens of the parish.
The clerk has an important role and can be a tremendous help to the council, but should follow policies laid down by the council.
There is no easy way to ensure that these things happen as they should. In the end, it will depend on there being sufficient interested citizens willing to stand as councillors, to argue principles, to seek publicity and eventually to get elected so as to bring about change by majority vote.