The rise and fall of the sea (4)
I believe the answer is:
tide
'the rise and fall of the sea' is the definition.
(the tide rises and falls)
This is the entire clue.
(Other definitions for tide that I've seen before include "Season; current" , "Ocean movement" , "Sea's ebb and flow" , "Periodic rise and fall of the sea" , "Moon-driven sea movement" .)