Williamseal, this is probably the toughest word puzzle of the year by far. The clues are very tough and the erratic nature of the entries makes it even tougher. Every year there are some tough puzzles like this to satisfy those who relish a very tough challenge, and also to reduce the number of all-correct solvers at various points during the year.
If you want to persevere you might consider 3, 6,, 8 (1 letter unclued) 14, 15, 18 (1 leetter unclued), 27 (1 letter unclued), 30a (anag. 1 letter unclued), 30b (hidden rev.), 31, 38 (hidden wiith 1 letter unclued, but ambiguous), 40, 40, 45, 48 (1 letter unclued), 50.
All those have reasonably straightforward clues.
I found filling the grid a tedious slog, and ambiguities in the answers/unclued letters of a couple of clues just irked me. Filling a grid like this is hard enough without the setter putting such obtacles in the way. I also think the first sentence of the preamble is completely inaccurate, and doesn't match the primary reference's entry for the significant word.