Marry and make a splash? (4,3,6)
I believe the answer is:
take the plunge
I believe this clue is a double definition.
'marry' is the first definition.
(take the plunge can informally mean get married)
'make a splash?' is the second definition.
(as in plunging into a pool)
'and' is the link.
(Other definitions for take the plunge that I've seen before include "Irrevocably commit oneself", "Commit oneself to a course of action", "Decide on bold action", "Bungee jumper has to", "do a bungee jump?".)