Possible Clues:

• Timidity is what's experienced by those suffering at the lowest level
• Chickening-out feeling
• Nervous of having twelve in them aged a century for legend, perhaps
• Chilly extremities due to fear
• In a small court what they used to charge for a TV series
• 'Aged a century on foot? Makes one nervous (4,4)'
• Icy extremities for slang fear
• Apprehension of Old Bill in court
• 'Perhaps legends aged a century make one apprehensive (4,4)'
• Loss of nerve, metaphorically