Sense of self-esteem (3)
I believe the answer is:
ego
'sense of self-esteem' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ego that I've seen before include "Part of the mind" , "Conscious mind" , "Aspect of the personality" , "Vowel to disappear, < say another" , "Self-esteem, sense of self" .)