Related Clues:

• It may be found in a proof
• Proof goof
• Error
• Erratum
• Printing mistake
• ThiS, e.g.
• Key blunder
• Printing goof
• Tit for tat, maybe?
• There's one et 24-Across
• Tears for Fears, e.g.
• Proofreader's concern
• Misprint, for short
• Slip on the galley
• Thsi is one