Space-saving device (3)
I believe the answer is:
etc
'space-saving device' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for etc that I've seen before include "'And the rest, in short (3)'" , "And so on, in brief" , "And so on, briefly" , "And so forth (abbr)" , "Etcetera (abbrev.)" .)