And that Clause is.....?
No my friend, we aren't going to play this stupid little game. The part which grants authority to defend the nation from dangerous threats is axiomatic. It does not need elucidation, no more than the word "Arms" has to define bullets.
We don't have to specifically mention "Asteroids steered onto our cities by foreign intervention" to understand that we have a right to defend against it.
All dangerous threats that have the potential to kill millions are defensible. There doesn't have to be specific authorization for each and every threat.