Possible Clues:

• Seen on 16 down
• Fleeting deviation from the norm
• Irregularity
• Plane, say, on a radar screen
• Spot of light on a radar screen, showing the position of an object
• Colonel losing millions: not what one expected?
• Hiccup taking first taste of brown sauce
• Initially believes lapse in progress is temporary setback
• Black sauce is something unusual
• Minor deviation, hiccup