Conviction that if overturned doesn't change (5)
I believe the answer is:
tenet
This clue is a double definition.
'conviction' is the first definition.
(thesaurus)
'if overturned doesn't change' is the second definition.
'that' is the link.
(Other definitions for tenet that I've seen before include "Item of belief" , "Conviction" , "A palindromic doctrine or creed" , "Rule" , "Palindromic principle or belief" .)