Possible Clues:

• Wall in
• Shut the headless fowl nearly up like this
• Totally surround
• Nearly kill intimate circle
• Include directions to cul-de-sac
• It's not far to the headless fowl, so shut up
• Near to where the hen has lost its head, shut it in
• Shut up when one is seen to have about 100500
• Pen this and mislay it at last
• Surround; place in envelope (with letter)