Author's alternative source (6)
I believe the answer is:
orwell
'author's' is the definition.
(I've seen this before)
'alternative source' is the wordplay.
'alternative' becomes 'or'.
'source' becomes 'well' (well is a kind of source).
'or'+'well'='ORWELL'
(Other definitions for orwell that I've seen before include "Eric Arthur Blair" , "George -, nineteen eighty four author" , "British novelist" , "Socialist author" , "George --, British author" .)