Saints often my sides in Rules (7)
I believe the answer is:
martyrs
'saints' is the definition.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for martyrs that I've seen before include "Persons suffering for their beliefs" , "Those dying for their belief" , "They suffer for a principle" , "people who suffer" , "People who die for their cause" .)