Possible Clues:

• Warning that's taken to heart again
• Going through that again - it will frighten one
• "If you don't eat your broccoli, I'll confiscate your phone," e.g
• One can be empty or veiled
• Indication of doom
• Statement of intent to do harm
• Risk of nurse taking heroin
• Time bomb, say
• That is round about such a bad promise
• Menace that encompasses regiment