Possible Clues:

• Poet with a German influence?
• Polymath who wrote "The Rubaiyat"
• ''The Rubáiyát'' poet
• Persian poet/astronomer/mathematician
• Poet, old character, needs grass mown -- may cut back
• In Irish county turned up token material for baleful old poet
• Poet translated by Edward Fitzgerald
• Persian mathematician known for his poetry
• 'Rubáiyát' poet
• Persian poet