Explorer has two positions on ship (7,4)
I believe the answer is:
captain cook
'ship' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'explorer has two positions' is the wordplay.
'explorer' becomes 'Cook' (c8th-century explorer Captain James Cook).
'has' means one lot of letters go next to another.
'two positions' becomes 'captain' (I can't explain this - if you can you should give a lot more credence to this answer).
'cook' put after 'captain' is 'CAPTAIN COOK'.
'on' is the link.
Can you help me to learn more?
(Other definitions for captain cook that I've seen before include "18th century navigator and explorer" , "English explorer, killed in Hawaii" , "New Zealand's charter" .)