Go under (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go under</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sink that I've seen before include "Subside" , "Washing-up place" , "Descend to a lower level" , "Slump" , "Pocket (billiards)" .)
(Other definitions for stopover that I've seen before include "Break in a journey" , "Overnight stay" , "Stay (of just one night?)" , "that hotel can provide?" , "bed and breakfast?" .)