One who wrote in defence of editorial sent up (5)
I believe the answer is:
defoe
'one who wrote' is the definition.
(novelist Daniel Defoe)
'in defence of editorial sent up' is the wordplay.
'in' indicates a hidden word.
'sent up' is a reversal indicator.
'eofed' is hidden in the letters of 'defence of editorial'.
'eofed' written backwards gives 'DEFOE'.
(Other definitions for defoe that I've seen before include "Daniel . . . . . wrote ''Robinson Crusoe'' (5)" , "Daniel, author of Robinson Crusoe" , "See 14" , "Daniel -, Moll Flanders author" , "Gulliver author" .)