Pupils study these citizens (8)
I believe the answer is:
subjects
I believe this clue is a double definition.
'pupils study these' is the first definition.
(school pupils study certain subjects)
'citizens' is the second definition.
(eg subjects of a monarch)
(Other definitions for subjects that I've seen before include "Areas for study or discussions" , "Topics or vassals" , "Things being discussed or people under rule" , "They owe allegiance to a monarch" , "things to discuss" .)