It is NITRIC. NIP is a word meaning to smart, and TRICK is a meaning of Rig, both of which have to be shortened. Kayakamina is also right about ROOKERY
It's not particularly clever. You should find a component of your missing answer in some of the other unclued words. All of the unclued answers exhibit one of three short words, which are hinted at by the phrase along the bottom, particularly the last word.
Sorry if that sounds complicated, but I haven't got my copy to hand