Answer for clue #4

First part: Using the City Hall window for the Main Street College of Arts & Sciences, you apply a line/word/letter cipher to just the college name to solve the first part of the clue. It will spell ENTER ROOM, SMALL CASE, ALICE CREATOR. Which tells you to go inside City Hall and look for a book case containing the book, Alice in Wonderland. 

Second part: The authors of these books are characters, and for the Alice in Wonderland book, the “author” is The Hatter. If you change A to I (as the clue directs), it spells HITTER.

The answer is HITTER.