Tardy or departed (4)
I believe the answer is:
late
I believe this is a double definition.
'tardy' is the first definition.
(I know that tardy can be written as late)
'departed' is the second definition.
(I've seen this before)
'or' acts as a link.
(Other definitions for late that I've seen before include "Still to come - already gone!" , "(Of a person) no longer alive" , "Yet to arrive?" , "Unpunctual or dead (4)" , "Tardy, slow" .)