Spirit never mixed (5)
I believe the answer is:
nerve
'spirit' is the definition.
(nerve is a kind of spirit)
'never mixed' is the wordplay.
'mixed' is an anagram indicator.
'never' is an anagram of 'NERVE'.
(Other definitions for nerve that I've seen before include "presumption" , "Boldness" , "Strand of body fibre" , "Sauce" , "Coolness under fire" .)