She should be told to shut up! The Clerk is there to ensure that the meeting is held legally and appropriately. The Chair controls the meeting and invites Councillors to speak at debate. the Clerk should be invited to offer an opinion if necessary but really should not get involved in the debates. There is no code of conduct for the Clerk but they should be expected to behave professionally. If you have a complaint against the Clerk, you should follow the council's complaints procedure that should cover this area, as well as complaints against councillors.