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' says the answer is hidden in the clue.
'OMIT' is hidden within '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" .)