Rise and fall of the sea (4)
I believe the answer is:
tide
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rise and fall of the sea</span>' is the definition.<br/ ><span class="explanation-format__explanation">(the tide rises and falls)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tide that I've seen before include "turning point" , "Something going in and out" , "Ebber and flower?" , "Rising and falling of the sea" , "Regular movement" .)