The author will read out loud a passage (5)
I believe the answer is:
aisle
'a passage' is the definition.
(aisle can mean a path or passageway)
'the author will read out loud' is the wordplay.
'the author' becomes 'ais' (I am not sure about this - if you are sure you should believe this answer much more).
'will' becomes 'll' (contracted form, as in 'he'll' - 'he will').
'read out loud' shows a homophone (sound like).
'll' sounds like 'le'.
'ais'+'le'='AISLE'
Can you help me to learn more?
(Other definitions for aisle that I've seen before include "part of theatre?" , "Passageway between seating areas" , "Extension of the nave in a church" , "'Passage, gangway (5)'" , "The way to get married in church?" .)