Possible Clues:

• Duty levied in some countries on goods entering town
• Short of one month, it's the duty of the king of France
• Leaders of off-shore court to rule on international tax
• After one month, in short, this might tax the king of France
• Old Roman local levy (not derived from 'eight')
• Old acts and droit without limits for city toll
• Local tax levied on certain articles
• The sound of attacks for a month at first
• Thirty-one days with French king on duty
• Tax demanded by foreign king at end of month