Possible Clues:

• Shakespeare's foot
• Foot for Frost
• Poetic foot with a short and long syllable
• Shakespeare's 'to be,' e.g
• Maya Angelou's foot
• Metrical unit, in odes
• One of two in 'The Grapes of Wrath'
• Foot on a page
• Foot of a poet
• Hamlet’s “to be,” e.g