Squire met a lot of the clues, but not the one I have in mind. I guess all episodes build up to the commercial breaks in a similar way, so, my next clue will be on episode content. 
Also, not Dagger of the Mind, though, I wouldn't mind thinking about Dr. Helen Noel, again....<sigh>
... oh yeah, another clue:
6th Clue: Normally a pacifist, Spock orders a crewman to use physical force and killing if necessary.

Also, not Dagger of the Mind, though, I wouldn't mind thinking about Dr. Helen Noel, again....<sigh>

6th Clue: Normally a pacifist, Spock orders a crewman to use physical force and killing if necessary.