Spirit, temperament (6)
I believe the answer is:
mettle
I believe this clue is a double definition.
'spirit' is the first definition.
(I know that mettle is a type of braveness)
'temperament' is the second definition.
(I've seen this before)
(Other definitions for mettle that I've seen before include "Spirit, resilience" , "Bravery" , "Spirit could sound like iron, say" , "boldness" , "Courage sounds like iron, for instance" .)