A North American dope at the back of the ship (5)
I believe the answer is:
apoop
'a north american' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'dope at the back of the ship' is the wordplay.
'dope' becomes 'poop' ('poop' can be a synonym of 'dope').
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the back of the ship' becomes 'a' (I can't justify this - if you can you should believe this answer much more).
'poop' put after 'a' is 'APOOP'.
Can you help me to learn more?
(Another definition for apoop that I've seen is " in the rear".)