I have tried numerous ways and get this error message
Can’t make «class NMCv» of selection of application "Numbers" into type string.
when I
set the clipboard to the value of the selection as string
I have also tried using:
tell application "System Events" to keystroke "c" using {command down}
with and without the brackets
In each case nothing is put into the clipboard. these seemed to have worked for others as I find them as answers to questions similar to this but they don't work for me.