Cards aboard ship? (5)
I believe the answer is:
decks
'cards aboard ship?' is the definition.
I can't tell whether this definition defines the answer.
'cards aboard ship?' is the wordplay.
'cards' becomes 'deck' (deck of cards).
'aboard ship?' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'deck'+'s'='DECKS'
Can you help me to learn more?
(Other definitions for decks that I've seen before include "Platforms on a vessel" , "Embellishes" , "Floors" , "Sets of cards" , "Packs of cards (US)" .)