I should have added above that I was at first convinced the setter had telescoped the two clues for 1 and 2 down. In 2, square = s...for = pro and duke = d usually, giving sprod which - believe it or not - is a name given to a salmon, the seeming keyword in 1!
In fact, I even imagined it might be deliberate and that we were supposed to put answers into different places throughout!
Hence my confusion over plaza.