Ocean-going craft? (10)
I believe the answer is:
seamanship
'ocean-going craft?' is the definition.
'seamanship' can be an answer for 'craft?' (thesaurus). I'm not certain of the 'ocean-going' bit.
'going craft?' is the wordplay.
'going' becomes 'seaman' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'craft?' becomes 'ship' (ship is a kind of craft).
'seaman'+'ship'='SEAMANSHIP'
Can you help me to learn more?
(Other definitions for seamanship that I've seen before include "Sailing skills" , "Skill of a sailor" .)