18ac)Fanny much in need of a battering runs off, weapon being withdrawn externally. (4,3)
N-N-/R-G
19ac)Motor ahead, one covered in crap (shit).(4.3)
P---/C-R
12ac)Free to backfire, bound to appear filthy.(7)
D-----D
(I think they may be in the Profannisaurus, and that's why I can't solve them! Whatever the reason, I think this puzzle is too hard for me).