Understand and rescue the shipwreck victim? (4,2,5)
I believe the answer is:
take on board
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for take on board that I've seen before include "opinion of directors" , "how to challenge company directors" , "what chess player will often do" , "Assimilate" , "what press gang would do" .)