Sad drop (4)
I believe the answer is:
tear
'sad drop' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tear that I've seen before include "A rip goes on a binge?" , "Rip or lacerate" , "'A rip, binge or drop of saline solution (4)'" , "Rip; salty drop" , "Rush - to pull apart" .)