Humble a graduate -- she has no heart (5)
I believe the answer is:
abase
'humble' is the definition.
('abase' can be a synonym of 'humble')
'a graduate she has no heart' is the wordplay.
'graduate' becomes 'ba'.
'has no heart' says to hollow out the word (remove centre letters).
'she' with its centre removed is 'se'.
'a'+'ba'+'se'='ABASE'
(Other definitions for abase that I've seen before include "Demean" , "Humiliate" , "Degrade (oneself)" , "Cast down" , "what 11 [REPRIMANDS] are meant to do" .)