Possible Clues:

• Foot of old companion jammed in box?
• In poetry, the reverse of an iamb
• Poetic foot
• As Yeats saw it, foot of mythological bird you once caught?
• European at back of sportsmen's line after twisting right foot
• Foot mythical bird put in the shoe, finally
• Counterpart of an iamb
• Metric foot; to cheer (anag.)
• Maestro cheekily clasping foot
• Yew, say, outside old church is a poetic feature