Thick socks might be the cure for this failure of courage (4,4)
I believe the answer is:
cold feet
'thick socks might be the cure for this failure of courage' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for cold feet that I've seen before include "Loss of courage or confidence" , "Feeling of fear - in lower extremities?" , "Apprehensiveness" , "result of paddling in winter ?" , "You might have them if you're afraid to proceed" .)