hi AJT, my interpretation is - IF 2D prime solution is NEON (4) and 12A sub is EON then 12D sub solution is a word not beginning with N but if fronted with N would = the prime solution of another clue. I also think the "something to drive" solution contains a vowel. Does that help or make it worse (-: ? Note that 22A/22D and 24A/24D each start with the same letter.