Duty before news time (7)
I believe the answer is:
tonnage
'duty' is the definition.
(I know that tonnage is a type of duty)
'before news time' is the wordplay.
'before' becomes 'to' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'news' becomes 'nn' (n is common abbrev for new, news can be plural).
'time' becomes 'age' (an age is a period of time).
'to'+'nn'+'age'='TONNAGE'
Can you help me to learn more?
(Other definitions for tonnage that I've seen before include "Measure of cargo space" , "Charge for carrying" , "Ship's size or carrying capacity" , "Weight of cargo - ship's carrying capacity" , "Capacity of ship" .)