A hearing detailed in chambers (5)
I believe the answer is:
atria
'chambers' is the definition.
(atrium is a kind of chamber)
'a hearing detailed' is the wordplay.
'hearing' becomes 'trial' (I've seen this before).
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'trial' with its final letter taken away is 'tria'.
'a'+'tria'='ATRIA'
'in' acts as a link.
(Other definitions for atria that I've seen before include "Central areas in buildings; open to the sky" , "Open-roofed courts" , "Public spaces with galleries" , "Upper chambers of the heart" , "entrances" .)