Part of roof falling reveals the innards (5)
I believe the answer is:
offal
'innards' is the definition.
(I have seen 'Edible innards' mean 'offal' so perhaps 'innards' could also mean 'offal')
'part of roof falling reveals' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'OFFAL' is hidden in the letters of 'roof falling reveals'.
'the' acts as a link.
(Other definitions for offal that I've seen before include "Butcher's stock" , "Worthless parts of animal carcass" , "cheap meat" , "Less edible parts of animal, entrails and organs" , "Liver, lungs etc" .)