Thanks to @Abide, and @Wendy Walker for test solving, and for some key fill/clue tweaks. Thanks also to Wendy for spotting a rather nasty red herring that I didn't even know was a fish.
Thanks as always to @Joe Ross for tech support.
The meta answer is a an appropriate 5-letter verb.
Cryptography
crosshare
PUZ
spreadsheet
I don't think it's especially difficult (maybe week 1.5 on the Gaffney scale), but if you get stuck, fear not, nudges will be forthcoming on Wednesday. Solution on Sunday.
Hope you enjoy!
cheers,
Alan