Mental health (6)
(Other definitions for morale that I've seen before include "Degree of optimism (of troops, perhaps)" , "Confidence, sense of wellbeing" , "Spirits" , "The spirit of a group or individual" , "Feeling of well-being" .)
'mental health' is the definition.
(sanity is a kind of mental health)
This is the entire clue.
(Other definitions for sanity that I've seen before include "State of having a healthy mind" , "Rational state" , "Mental normality" , "Rationality" , "Reason and coherence" .)