Related Clues:

• "Oops, I messed up"
• "Oops, sorry!"
• Teacher wearing a perm, awfully sorry?
• Sorry fellow more disheartened coming below average
• 'Oopsie!'... and a hint to the ends of 18-, 25-, 39- and 50-Across
• Name-drop outrageously? I do apologise
• "I'm to blame"