I am a word of 12 letters. My 12, 4, 7, 2, 5 is an Eastern beast of burden. My 1, 8, 10, 9 is a street made famous by Sinclair Lewis. My 11, 3,6 is past. My whole is a person suffering from delusions of greatness. So, who am I?
THE SOLUTION
Camel, Main, ago; megalomaniac.