Related Clues:

• Operation to surround and cut off supplies
• Surrounding blockade
• Investment but not necessarily of capital
• Spotted American inside — kept going
• Besetting sin, not trendy, say, within limits of indolence
• Starving-out operation
• Investment (of town)
• Unrelenting bowling spell
• Shaw's investment
• Kept (something) going
• A prolonged attack
• Military operation surrounding a town
• Steady and continuous
• Blockade of a fortress
• Operation to surround a town/fortress