Neglect to return from Baltimore (4)
I believe the answer is:
omit
'neglect' is the definition.
('omit' can be a synonym of 'neglect')
'return from baltimore' is the wordplay.
'return' says the letters should be written backwards.
'from' indicates a hidden word.
'timo' can be found hidden inside 'baltimore'.
'timo' reversed gives 'OMIT'.
'to' is the link.
(Other definitions for omit that I've seen before include "Disregard" , "Leave out or undone" , "Fail to use" , "Leave out, perhaps in error" , "Exclude; forget to include" .)