Dive (3)
'dive' is the definition.
(I know that dive can be written as plunge)
This is the entire clue.
(Other definitions for plunge that I've seen before include "Thrust or dive into" , "Fall suddenly and uncontrollably" , "Sudden drop" , "Pitch" , "take a dip in the pool" .)
'dive' is the definition.
(I know that dip is a type of dive)
This is all the clue.
(Other definitions for dip that I've seen before include "Lower into liquid" , "Lower into water for short swim" , "Sink downwards" , "Decline" , "Informally a short bathe" .)