Sailor nearly lost gold aboard craft (8)
I believe the answer is:
argonaut
'sailor' is the definition.
(I have seen 'Classical sailor' mean 'argonaut' so perhaps 'sailor' could also mean 'argonaut')
'nearly lost gold aboard craft' is the wordplay.
'nearly lost' becomes 'gon' (I can't explain this - if you can you should give a lot more credence to this answer).
'gold' becomes 'au' ('Au' can be a synonym of 'gold').
'aboard' means one lot of letters goes inside another.
'craft' becomes 'art' (I've seen this before).
'gon'+'au'='gonau'
'gonau' put inside 'art' is 'ARGONAUT'.
Can you help me to learn more?
(Other definitions for argonaut that I've seen before include "Follower of Jason in search for Golden Fleece" , "One of Jason's crew" , "Member of Jason's crew" , "Old quester" , "legendary sailor" .)