Leaves out some whom I.T. suggests (5)
I believe the answer is:
omits
'leaves out' is the definition.
('omit' can be a synonym of 'leave out')
'some whom i t suggests' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'OMITS' can be found hidden inside 'whom i t suggests'.
(Other definitions for omits that I've seen before include "Forgets" , "skips" , "overlooks" , "Leaves out or neglects" , "misses out" .)