Run away to sea? (3)
I believe the answer is:
ebb
'run' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ebb that I've seen before include "Flow outwards" , "Go out or recede like tide" , "Tidal outflow" , "Outward flow of the tide" , "Receding movement, as of a tide" .)