Jail room (4)
I believe the answer is:
cell
'jail room' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cell that I've seen before include "Spreadsheet unit" , "Place of incarceration or unit of living matter" , "Place of incarceration in body unit" , "Animal or plant building unit" , "Small room for nun, monk or prisoner" .)