Possible Clues:

• Plain figure?
• Yellowstone beasts
• Old West herd
• Buffalo Bill's prey
• Largest terrestrial North American mammal
• Animal featured on the flag of Wyoming
• So it's in the nib that that is so largely beastly!
• Animal that consequently gets stuck into a wine container
• So it is beastly big in the big container
• Shaggy Westerners