Righteous esprit de corps lacks point (5)
I believe the answer is:
moral
'righteous' is the definition.
(I've seen this before)
'esprit de corps lacks point' is the wordplay.
'esprit de corps' becomes 'morale' ('morale' can be a synonym of 'esprit de corps').
'lacks' indicates named letters should be taken away.
'point' becomes 'e' (E is an example).
'morale' with 'e' removed is 'MORAL'.
(Other definitions for moral that I've seen before include "Behaving ethically" , "Honourable" , "Relating to principles of right and wrong" , "Practical lesson to be drawn from an experience" , "Virtuous and principled" .)