Leaves out of room itself (5)
I believe the answer is:
omits
'leaves out' is the definition.
('omit' can be a synonym of 'leave out')
'of room itself' is the wordplay.
'of' indicates the answer is hidden within the clue.
'OMITS' can be found hidden inside 'room itself'.
(Other definitions for omits that I've seen before include "Leaves out or neglects" , "overlooks" , "misses out" , "Forgets" , "skips" .)