Hints:
8 down is a noun, not an adjective. Books might have been written on it, certainly chapters.
4 across - just look at the chessboard...
7 across - played lots of games against Morphy
14 across - these are given name initials, the answer is a surname
More useful hints:
Hints:
8 down is a noun, not an adjective. Books might have been written on it, certainly chapters. When writing about pawn structure, masters often say that "the white squares are showing ___________" in a position.
4 across - just look at the chessboard...They go across the chessboard...
7 across - played lots of games against Morphy. Morphy would give him pawn or knight odds, and win most of the time
14 across - these are given name initials, the answer is a surname. The guy was on the losing side of the "Immortal Game."
Well, with those clues given, 14 across must be Kieseritzky.
I think 4 across is intended to be Diagonal, although I don't like the choice of clue.
I still don't know the other two, however! 
Is 8 down weakness? I havnt been on here 4 ages, missed out a month =D dunno why, i just quit =(
And i think 4 is diagonal,
3rd letter = a
5th = o
6th = a
Ah yes, 8 down is probably weakness, nice spot Lord-Chaos.
Now we just need to find someone who enjoyed losing chess games to Morphy.
Wait, I believe I have it!
7 across is (hopefully) Maurian. (As in Charles Maurian.)
Assuming I am correct, we have completed the crossword! Huzzah!
Oops, that is why I do not do crosswords.