Neglected (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">neglected</span>' is the definition.<br/ ><span class="explanation-format__explanation">('omit' can be a synonym of 'neglect')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for omitted that I've seen before include "Failed" , "Hairdressing" , "let go" , "forgotten" , "Left out - neglected" .)
(Other definitions for disused that I've seen before include "empty" , "Derelict" , "No longer observed or practised" , "Idle" , "No longer in action" .)