I'm ready for anything, so tackle book about origin of crosswords (4,2,2,2)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

SO + KIT [tackle] + TOME [book] round C [first letter – origin – of Crosswords] – John Halpern [Paul] has written several books about crosswords, including ‘The History of the Crossword’ – great clue