Regulations of frontiers without opening (6)
I believe the answer is:
orders
'regulations' is the definition.
The answer and definition can be both acts as well as being plural nouns.
Perhaps you can see a link between them that I can't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for orders that I've seen before include "Monastic societies" , "Dictates, decrees" , "Groups living under particular religious rules" , "Commands these priests and nuns?" , "Given to soldiers" .)