Thanks for that Campanilla.
Although I think the connection you suggest is quite tenuous, it is a straw well-clutched.
Anyway, there have been several 'zero' initiatives out of America (California's Zero-Emission Vehicle (ZEV) Mandate, New York's 'zero tolerance' policing initiative etc...).
Now wondering if the answer isn't 'zero' (unlikely), that the clue is a bit rubbish (likely) or that there's a clever and obvious explanation for 'zero' that we've missed (absolutely & entirely improbable)?
Are there any other crossing letters other than second letter 'e'?
I was so hoping that the answer might be (Ca)
nada, but that seems destined not to be.
Best Wishes.
JimC