Possible Clues:

• Opens the door to
• Concedes
• What's so sad about Tim is that he agrees he did it
• Takes in a desperate man if terribly sick on first inspection
• Lets in or owns up
• Allows to 31 across, or so one confesses
• Does not deny it is past the year 1000
• Lets in and confesses
• What a skylight does to sunlight
• Lets it out that it lets you in