Concerned editor is after book alternative (8)
I believe the answer is:
bothered
'concerned' is the definition.
(thesaurus)
'editor is after book alternative' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'is after' means one lot of letters go next to another.
'book' becomes 'b' (abbreviation for book).
'alternative' becomes 'other' (I've seen this before).
'b'+'other'='bother'
'ed' put after 'bother' is 'BOTHERED'.
(Other definitions for bothered that I've seen before include "Made an effort -- put out" , "Was a pest" , "Hot and exasperated" , "Old song: 'Bewitched, . . . . . . . . and bewildered'" , "Under stress" .)