Possible Clues:

• Babe, e.g.
• Animal that can precede the starts of 20-, 30-, 36-, 46- and 52-Across
• ''Oink'' producer
• Screen's Babe
• Orwell's Napoleon, for one
• Boar, e.g
• Overeat (with "out")
• Selfish sort
• Potbellied critter
• Petunia, for one