I am now down to 3 clues: L often confused with numeral this order of magnitude larger (6), Single US bomber, missing camp, heading north (4), Spenser's put on to drive around Germany (4). I think the first and third start with the same letter and that the second is originally a five-letter word which loses N to become the name of a plant. Also, is what is to be written below the grid a phrase or two separate words? Any hints/nudges in the right direction would be appreciated.