If a book title within an essay title is not italicized in the source, should I italicize it in my works-cited-list entry?
Yes. A title within a title should be styled according to the guidelines in section 1.2.4 of the MLA Handbook, regardless of how a title within a title is styled in the source.
For example, the title of an essay about Gone with the Wind is styled in EBSCOHost as follows:
“Painfully Southern”: “Gone with the Wind,” the Agrarians, and the Battle for the New South
Since Gone with the Wind is the title of a novel, if you were to include this essay in your works-cited list, you would set it in italics instead of enclosing it in quotation marks:
Adams, Amanda. “‘Painfully Southern’: Gone with the Wind, the Agrarians, and the Battle for the New South.” Southern Literary Journal, vol. 40, no. 1, Fall 2007, p. 58. EBSCOHost Connection, connection.ebscohost.com/c/literary-criticism/28439869/painfully-southern-gone-wind-agrarians-battle-new-south.