Periodic rise and fall (4)

I believe the answer is:

tide

(Other definitions for tide that I've seen before include "Current, ebb" , "Regular movement" , "Powerful surge" , "It ebbs and flows" , "Ocean phase" .)

I've seen this clue in the Sydney Morning Herald.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.