symmetry ..possibly ....if 7a is 8 letters then the last across would also be 8 letters?
Similarly if 2d were 7 letters then the answer at the bottom of the 5d column would also be 7 letters....
Hope I'm on the right lines here....
Symmetry.
Difficult to spell this out without giving too much away. What it means is that if you rotate the grid by 180 degrees there is a feature of the entries in the new positions that is the same as the original. However, you need to work out what that feature is. Hope that makes sense.
Castafiore
Everyone has worked out that the number of letters in the solutions exceeds the number of spaces in the grid, of course. Question is: how can that be accommodated?