Possible Clues:

• Fictional giant
• Sinus specialist, succinctly
• Suffix with exist or insist
• Forest friend of Frodo
• One of a race in Middle-earth
• Forest creature in 'The Lord of the Rings'
• Tolkien behemoth
• Treelike creature in 'The Lord of the Rings'
• Dr. who treats snorers
• Fangorn Forest inhabitant