Keep preserving the standard (5)
I believe the answer is:
canon
'the standard' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for canon that I've seen before include "senior cleric" , "General principle or kind of clergyman" , "Criterion; church official" , "Ecclesiastical rule" , "Principle; list of recognised works" .)