Permanently requiring rule too (3,4,7)
I believe the answer is:
for good measure
'too' is the definition.
Both the answer and definition are adverbs. Perhaps there's an association between them I don't understand?
'permanently requiring rule' is the wordplay.
'permanently' becomes 'for good' (synonyms).
'requiring rule' becomes 'measure' (I am not sure about this - if you are sure you should believe this answer much more).
'forgood'+'measure'='FOR GOOD MEASURE'
Can you help me to learn more?
(Other definitions for for good measure that I've seen before include "in addition?" , "as finishing touch?" , "as well" , "Why we calibrate scales" , "as an extra precaution" .)