Decisions are made by the council. The clerk is there to advise, and will usually have a greater understanding of the relevant legislation, so that the clerk's advice should always be taken into consideration. It is not binding, though. The clerk may also have delegated powers, decided by the council. In general, it's better if the clerk can get on with the job without consulting the council on every trifling matter. But it is up to the council to decide what power is delegated to the clerk, or to vary it.
Likewise, individual councillors have no powers of their own, and can only act on decisions made by the council.
Of course it all works best when people cooperate. Maybe you're in a good position to make a start on the book!