Related Clues:

• It starts to be in the water when you make a hole in it
• If you get your knife into them they come out backwards at night
• In us it's all in vain, by the sound of it
• Just a bit about R to be able to go through with it
• They're fly enough to come back to drive the point home
• Are in a bit and go through with it
• They come back at night with a knife
• That's not all in vain, by the sound of it
• The fly-by-nights come back in a piercing way
• Do the fly-by-nights return to get their knife into you?
• They might come back by night with a dagger (4)
• Take a knife to the fly-by-nights back there
• A bit about R is needed to go through with it
• Are, in short, in a bit you might make a hole in
• Not blue for the 19 across