What is the Latin for they did it?

if you need this for the daily mail's smallest, hardest crossWord. the answer is

FF

it's an abbreviation. although i'm not sure what of. the clue is

(L) they did it (abbr)

other answers are EKKA HOB FOB FROG KHOR KOBO AB FF

Hope that helps :) it took an hours googling to get those!