I got it right?! Yay! I deserve cake and a round of applause from the rest of the class. I think I was supposed to provide a clue? Sorry, too hard for me. PS: Funny note: in Portuguese, “straight straits” would be estreitos estreitos (straight straights) Homonym words. Maybe that’s how I got there so quickly.
principal principal Not sure if that counts as a homophone given the same spelling and closely related meanings and origins but anyway. Clue: Unproductive inspiration
'principle' is "a fundamental truth or proposition that serves as the foundation for a system of belief or behaviour or for a chain of reasoning." 'principal' is "first in order of importance; main." use of 'primary' suggests the latter.
True. I think the @Friedrich Kugelschreiber probably meant the answer to be "principal principle". The clue was wrong as you said, in that case.