It's written and enclosed (6)
I believe the answer is:
penned
I believe this clue is a double definition.
'it's written' is the first definition.
(written with a pen)
'enclosed' is the second definition.
(similar in meaning)
'and' acts as a link.
(Other definitions for penned that I've seen before include "Corralled" , "Shut in" , "Caged, wrote" , "Wrote; enclosed" , "in captivity" .)