Writer gave up on Old English (5)
I believe the answer is:
defoe
'writer' is the definition.
(Daniel Defoe)
'gave up on old english' is the wordplay.
'gave' becomes 'fed' ('feed' can be a synonym of 'give').
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'on' is a charade indicator (letters next to each other).
'old english' becomes 'oe'.
'fed' backwards is 'def'.
'def'+'oe'='DEFOE'
(Other definitions for defoe that I've seen before include "Author of Robinson Crusoe, d. 1731" , "Gulliver author" , "See 14" , "Daniel --, English novelist" , "Daniel ---, wrote Moll Flanders" .)