Possible Clues:

• Empty space within
• Cavity or space in something
• Sounds as if the whole of it is in the middle (6)
• Not solid, having hole in the middle
• Like jack-o'-lanterns
• Lacking substance
• Howl miserably, left with nothing through Depression
• O, fifty-fifty has nothing in how it gets around
• Like a log you can look inside of
• An empty space within