The landlord visited a guy who was six months behind with his rent and found him dead in the house.
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means stagnate. The verb vocab version is to be overdue. This is probably because something that has stagnated is running late, and therefore causes it to be overdue.
The reading for this one is wildsauce. I'm going to leave this one to your capable hands. Just think of Tod (とど) and some coot (こお) doing something wild even though they're overdue for something else, or something. Anyways, best of luck to you on this one.