Leave out of room itself (4)
I believe the answer is:
omit
'leave out' is the definition.
(I know that leave out can be written as omit)
'of room itself' is the wordplay.
'of' indicates the answer is hidden within the clue.
'OMIT' is hidden in the letters of 'room itself'.
(Other definitions for omit that I've seen before include "Leave out or overlook" , "Leave out or fail to do" , "Drop" , "Exclude; veto" , "Leave out, perhaps in error" .)