Dramatic drop (6)
I believe the answer is:
plunge
'dramatic drop' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for plunge that I've seen before include "Dive or throw into" , "Take the . . . . . . - jump right in" , "Drop steeply" , "Take the . . . . . . - dive right in" , "A steep drop" .)