It's carried once more in battle (7)
I believe the answer is:
freight
'it's carried' is the definition.
I can't judge whether this definition defines the answer.
'once more in battle' is the wordplay.
'once more' becomes 're' (prefix in words like 're-emerge' or 're-enter').
'in' is an insertion indicator.
'battle' becomes 'fight' (fight is a kind of battle).
're' going inside 'fight' is 'FREIGHT'.
Can you help me to learn more?
(Other definitions for freight that I've seen before include "Goods carries by large vehicle" , "Goods in transit" , "Goods carried by a large vehicle" , "Something carried" , "Commercial transport" .)