This is a normal crossword, except that three of the entries (8-Across, 23-Across, and 15-Down) are unclued. The completed grid looks like this:
In clue order, the three unclued entries make the phrase FEAR TOWARD THIRTEEN. This is a clue for the answer, TRISKAIDEKAPHOBIA. One extra nod to this is that the grid for this puzzle is 13×13.