I'll be heard in passage (5)
I believe the answer is:
aisle
'passage' is the definition.
(aisle can mean a path or passageway)
'i'll be heard' is the wordplay.
'be heard' indicates a 'sounds like' (homophone) clue.
'ill' sounds like 'AISLE'.
'in' is the link.
(Other definitions for aisle that I've seen before include "Passage between rows of seats" , "that would-be bride hopes to make it up!" , "part of theatre?" , "Passageway between blocks of seats" , "Supermarket passageway" .)