In sound flood rescue vessel reveals bow (3)
I believe the answer is:
arc
'bow' is the definition.
(both can mean a curve)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for arc that I've seen before include "Curve of car" , "Bend" , "Part of curved line" , "Curvature" , "circle? Not entirely" .)