Act like any would, when just starting out (3)
I believe the answer is:
law
'act' is the definition.
(law is a kind of act)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for law that I've seen before include "Set of rules laid down by authority" , "Rule, statute" , "Collection of rules imposed by authority" , "Official rule" , "Edict" .)