be a devil—
1. (imper.) is used as a humorous expression of encouragement to persuade a person to do smth.:
- Be a devil and order us a bottle of wine!
2. be extremely bad or immoral:
- He was a devil to those of us who thought the war was stupid and pointless. He personified the arbitrary power of the draft…
be the very devil—1. (also: be the devil incarnate) = be a devil 2:
- Though he was a hero to some, he was the very devil to others.
2. (of a situation) be very difficult or annoying:
- My car is super to drive, but it’s so big it’s the very devil to find a parking place for it.