Enclosed around half of a local area (7)
I believe the answer is:
endemic
'a local area' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'enclosed around half' is the wordplay.
'enclosed' becomes 'enc' (abbreviation for 'enclosed' as in letters).
'around' indicates putting letters inside.
'half' becomes 'demi' (prefix as in 'demigod').
'enc' going around 'demi' is 'ENDEMIC'.
'of' is the link.
Can you help me to learn more?
(Other definitions for endemic that I've seen before include "Commonly found in particular place - may be disease" , "Regularly occurring, disease say" , "Peculiar to local area" , "Restricted to a certain area" , "locally confined" .)