Possible Clues:

• Stars offering old jokes on island
• Ambitious zodiac sign
• Sign of company, with navy south of island
• Sign top player at last — current seed
• Sign of growth to the south of island in the Tyrrhenian Sea
• Problem for walker on island, needing sign
• Sign up Republican in party under Ford in the '70s?
• Goat of the zodiac
• Tropical crop from the Mediterranean?
• Mediterranean island crop one delivered in early January