French number in cargo (7)
I believe the answer is:
freight
'cargo' is the definition.
(I know that cargo can be written as freight)
'french number' is the wordplay.
'french' becomes 'fr' (abbreviation).
'number' becomes 'eight' (eight is a kind of number).
'fr'+'eight'='FREIGHT'
'in' acts as a link.
(Other definitions for freight that I've seen before include "Goods in transit" , "Goods carried by a large vehicle" , "Something carried" , "Transport of bulk goods" , "Goods carries by large vehicle" .)