Courage never changes (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
nerve
'courage' is the definition.
(I know that nerve is a type of courage)
'never changes' is the wordplay.
'changes' is an anagram indicator.
'never' is an anagram of 'NERVE'.
(Other definitions for nerve that I've seen before include "Dangerous type of gas" , "Impudence (colloq.)" , "Impudence; courage" , "Coolness under fire" , "presumption" .)