Protégé observed centre of iris (5)
I believe the answer is:
pupil
This clue could be a double definition.
'protege' is the first definition.
(I've seen this in another clue)
'iris' is the second definition.
(thesaurus)
'observed centre of' acts as a link.
This may not be right. Some or all of it may belong to one of the definitions.
Can you help me to learn more?
(Other definitions for pupil that I've seen before include "bit of a looker" , "Schoolchild; part of eye" , "Dark centre of the eye" , "One being taught" , "Learner in the eye?" .)