Quiet at the back of passage (5)
I believe the answer is:
shaft
'passage' is the definition.
(shaft is a kind of passage)
'quiet at the back' is the wordplay.
'quiet' becomes 'sh'.
'at' says to put letters next to each other.
'the back' becomes 'aft' (I've seen this before**).
'sh'+'aft'='SHAFT'
'of' acts as a link.
(Other definitions for shaft that I've seen before include "Arrow part" , "Long rod or column of light" , "Beam of light" , "Ray of light; treat unfairly" , "Vertical passageway, into a mine say" .)