My guess is that the wrong day's clues have been printed. According to the clues there should be four answers of two letters but in the grid there are only two. No wonder they call it the world's smallest, hardest crossword!
It's the grid that's wrong. I've reconstructed it. You remove the "blocks" from the outside and put them diagonally in the middle, Then fill in 1a and 1d (4 letters each), and the rest does itself, really.