French crew boxes on ship (7)
I believe the answer is:
freight
'boxes on ship' is the definition.
(freight means items being transported)
'french crew' is the wordplay.
'french' becomes 'fr' (abbreviation).
'crew' becomes 'eight' (an eight-person rowing team).
'fr'+'eight'='FREIGHT'
(Other definitions for freight that I've seen before include "Something carried" , "Transport of bulk goods" , "that's carried by rail and road" , "Consignment" , "Goods in transit" .)