Christopher —, author (9)
I believe the answer is:
isherwood
This clue is a double definition.
'christopher' is the first definition.
(I've seen this before)
'author' is the second definition.
(I know that Isherwood is a author)
(Other definitions for isherwood that I've seen before include "writer" , "Christopher ---, C20 novelist" , "Author" , "Christopher --, novelist and dramatist" , "Christopher --, novelist (Goodbye to Berlin)" .)