Courage is never wasted (5)
I believe the answer is:
nerve
'courage' is the definition.
(I know that nerve is a type of courage)
'never wasted' is the wordplay.
'wasted' indicates an anagram.
'never' with letters rearranged gives 'NERVE'.
'is' is the link.
(Other definitions for nerve that I've seen before include "presumption" , "Sensitive fibre in the body" , "Grit" , "Body fibre conveying sensations to brain" , "Impulse transmitter - bottle" .)