Rule internally flawed (3)

I believe the answer is:
law
'rule' is the definition.
(law is a kind of rule)
'internally flawed' is the wordplay.
'internally' indicates a hidden word.
'LAW' is hidden within 'flawed'.
(Other definitions for law that I've seen before include "Collection of rules for a society" , "'Possession is nine points of the ...'" , "Official rule" , "Body of rules of conduct for a society" , "at 16 down [MAN UNITED]" .)