It's said the writer's going to Corfu, possibly (4)
I believe the answer is:
isle
'corfu possibly' is the definition.
(Corfu is an example of an island)
'it's said the writer's going to' is the wordplay.
'it's said' shows a homophone (sound like).
'the writer's going to' becomes 'I'll' ('I will', referring to the person writing).
'ill' is a homophone of 'ISLE'.
(Other definitions for isle that I've seen before include "small piece of land" , "Fair ---, knitting style" , "Skye, for example" , "I shall hear" , "Piece of land in water" .)