Concerned one new setter upset editor (10)
I believe the answer is:
interested
'concerned' is the definition.
(I know that concerned can be written as interested)
'one new setter upset editor' is the wordplay.
'one' becomes 'i' (Roman numeral).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'upset' indicates anagramming the letters.
'editor' becomes 'ed' (abbreviation).
'setter' anagrammed gives 'terest'.
'i'+'n'+'terest'+'ed'='INTERESTED'
(Other definitions for interested that I've seen before include "Not impartial" , "Concerned" , "Attentive" , "Showing curiosity" , "Wanting to know" .)