12a: Though it's less, put your name to it - this is it. (5,4). As it was the 5th clue across, I answered 'fifth clue'. Alas, this doesn't seem to fit with other answers.
15d: Are spuds suitable to serve with minced pork joints? (4) _ _ S H. Mash?
16a: Princess is returning to foreign city. (6) S _ E _ _ _.
15a: The type in my letters is liquid, white and opaque. (5) _ _ _ _ Y.