Ship's cook? (7)
I believe the answer is:
steamer
'ship's' is the definition.
(steamer is a kind of ship)
'cook?' is the wordplay.
I cannot really understand how this works, but
'cook?' could be 'steam' (steaming is a kind of cooking) and 'steam' is located in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
(Other definitions for steamer that I've seen before include "Boat; type of saucepan" , "Cooker; ship" , "Cooking apparatus" , "Ocean liner" , "Kitchen pan; ship" .)