Here's an example of a zero derivation but instead of verbing, we're nouning.
Merriam-Webster's Collegiate Dictionary online edition actually says that quote has been used as a noun since 1888. This is probably long enough to satisfy even William Safire. Still, I bet someone nouned it back in 1888. (The verb form's been around since at least 1582 and Merrian-Webster pegs quotation at 1646.)