Christianity, for instance (8)
I believe the answer is:
religion
'christianity for instance' is the definition.
(I know that Christian religion is a type of religion)
This is the entire clue.
(Other definitions for religion that I've seen before include "Belief - way of life of monks and nuns" , "Marx's pium of the people" , "Organised system of faith" , "System of divine worship" , "Institution to express belief in a divine power" .)