Possible Clues:

• Vegetable, source of iron
• Florentine recipe feature
• V-8 ingredient
• Bites back endless pain from plant
• In trouble, Popeye's opening his can -- of this?
• Popeye's 'fuel'
• Plant of the goosefoot family, its young leaves used as a vegetable
• Cook panics getting hot food for Popeye
• Leaves with story about making Cornish pasty
• After opening of shop, steal, pocketing a vegetable