The writer’s staff returned to really empty sleeping quarters (9)
I believe the answer is:
'sleeping quarters' is the definition.
(I've seen this before)
'the writer's staff returned to really empty' is the wordplay.
'the writer's' becomes 'im' (both could mean 'the crossword setter is').
'staff' becomes 'rod' (I've seen this before).
'returned' shows that the letters should be reversed in order.
'empty' says to hollow out the word (remove centre letters).
'really' with its middle removed is 'ry'.
'imrod' written backwards gives 'dormi'.
(Other definitions for dormitory that I've seen before include "where Tom Brown slept" , "Bedroom with several beds" , "Large sleeping room" , "Dirty room (anag.)" , "Communal bedroom" .)