Possible Clues:

• Food from the earth -- 500 pounds to an aficionado
• Financial obsessive accepts knighthood, finding source of oil
• Food from the earth — £500 to an aficionado
• Not my nuke (anag.)
• Pulse brisk ultimately in one obsessed with material gain?
• Scamp with fruitcake, and something else to eat
• My nuke not exploding in plant
• It's ground like a mad sort of 23 down