Author is defied, alone, upset (6,5)
I believe the answer is:
daniel defoe
'author' is the definition.
(I've seen this before)
'defied alone upset' is the wordplay.
'upset' is an anagram indicator.
'defied'+'alone'='defiedalone'
'defiedalone' is an anagram of 'DANIEL DEFOE'.
'is' acts as a link.
(Other definitions for daniel defoe that I've seen before include "Moll Flanders writer" , "Novelist" , "Author" .)