What ebbs and flows (4)
I believe the answer is:
tide
(Other definitions for tide that I've seen before include "Ebb and flow of the sea" , "Season; current" , "Movement of seawater" , "One thing that waits for no man" , "Ocean movement" .)
I believe the answer is:
tide
(Other definitions for tide that I've seen before include "Ebb and flow of the sea" , "Season; current" , "Movement of seawater" , "One thing that waits for no man" , "Ocean movement" .)