Vessel to rescue people at sea (8)
I believe the answer is:
lifeboat
'vessel to rescue people at sea' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for lifeboat that I've seen before include "needed if ship sinks" , "Vessel to rescue people at sea" , "Sea rescue craft" , "Take to it if the ship is sinking" , "To fable I turn if in danger of sinking" .)