Like some promises (5)
I believe the answer is:
empty
'like some promises' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for empty that I've seen before include "Drained glass" , "Unfilled" , "Devoid of content" , "left for the milkman?" , "Like the sherry decanter by the time gran's jolly" .)