Answer:
A huge mythical animal said to resemble a whale.
My first is twice in apple but not once in tart. My second is in liver but not in heart. My third is in giant and also in ghost. Whole I'm best when I am toast.
The homes of tiny creatures that collect in corners if you aren't vigilant about dusting.
I'm a lion with a human head. Guess my Riddle or you'll be dead.
Those with eyes bigger than their stomach will definitely leave the restaurant with one of them. It is named after a house pet as well.
They come to witness the night without being called, a sailor's guide and a poet's tears. They are lost to the sight each day without the hand of a thief.