Related Clues:

• One isn't but two is
• Not so odd that it should come late in the day for the poet
• There's nothing odd in 4/5 of 7
• 'The poetic opposite of 17 across, and that's flat (4)'
• That's poetic of late but one is not
• One's not what two is
• Two is, one isn't
• 4/5 x 7. Not so odd
• It's poetically late to be like 8 across
• Exactly divisible by two
• Not so odd that it's not early for the poet
• What two is that one's not
• Word with "break" or "get"
• Not notched
• Odd's counterpart