Passage the writer will read aloud (5)
I believe the answer is:
aisle
'passage' is the definition.
(aisle is a kind of passage)
'the writer will read aloud' is the wordplay.
'the writer will' becomes 'ill' (I'll, i.e. 'the person writing the crossword will').
'read aloud' shows a homophone (sound like).
'ill' is a homophone of 'AISLE'.
(Other definitions for aisle that I've seen before include "Passage between blocks of chairs" , "Passage between rows of seats" , "Supermarket passageway" , "lateral strip" , "channel" .)