Necromancer is reportedly captivated by protégé (6)
I believe the answer is:
wizard
'necromancer' is the definition.
(synonyms)
'reportedly captivated by protege' is the wordplay.
'reportedly' becomes 'iz' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'captivated by' indicates putting letters inside.
'protege' becomes 'ward' (both can mean a child in someone's care).
'iz' going inside 'ward' is 'WIZARD'.
'is' is the link.
Can you help me to learn more?
(Other definitions for wizard that I've seen before include "Fantastic" , "Genius" , "A magician, perhaps from Oz" , "Superb" , "One who practices magic or sorcery" .)