Related Clues:

• Physical prevention of access
• Isolation of place by sea
• Prevention of access and egress
• Prevent(ion of) access and exit
• Ambush — mug — criticise — fit
• Offensive move
• Trade barrier
• "Sic 'em!"
• Closure of port to prevent entry or exit
• Can't get through bar to Bill on boat
• Go for tips from Clark Kent after a time looking in the mirror
• Sea wall?
• A time to change course that's fit
• Occupied with change of course in storm
• Invade; vilify