Today’s Saturday Stumper

Today’s Newsday  Saturday Stumper, by David P. Williams, is both terrific and terrifically frustrating. The northwest corner? Why, this puzzle is doing itself. Elsewhere, far more difficulty. And there’s a confounding cross that left me one letter short of solving.

Some clue-and-answer pairs of note:

3-D, fifteen letters, “Anger management candidate.” I’ve known one or two.

5-D, thirteen letters, “Insignificant.” I wrote in the answer with one cross, no hesitation. Yes, the puzzle was doing itself.

9-D, seven letters, “Fire-proofing.” I think the answer has to be understood as a noun.

15-A, four letters, “Inside plant.” See also “Inside plants,” 40-D and 45-D, five letters each.

17-A, fifteen letters, “A handful.” I wrote in the answer with no crosses, no hesitation. Yes, the puzzle was still doing itself.

19-D, thirteen letters, “Industrialists, often.” I’m glad I can spell well.

21-A, four letters, “She’s seen in nail salons.” Not MADGE.

25-D, five letters, “White house rotunda.” Not in danger of being torn down.

31-A, eleven letters, “Busy work.” I’m not sure that “busy work” means that.

48-A, six letters, “She’s next to her boyfriend on Hollywood Boulevard.” Ha.

52-A, three letters, “You, in informal phrases.” I can’t recall ever seeing this answer in a crossword.

53-A, fifteen letters, “Improper influencer.” Another fine long answer.

The problem spot for me: 51-D, four letters, “Word below some Treasurer’s signatures” and 57-A, four letters, “A thing of the past.” I have no idea what the first answer means. And the second clue appears to ask for a noun.

My favorite in this puzzle: 34-A, three letters, “Planet precursor,” because this tiny answer broke things open for me.

No spoilers; the answers are in the comments.