What's carried about in box? (7)
I believe the answer is:
freight
'box?' is the definition.
(thesaurus)
'what's carried about' is the wordplay.
'what's' becomes 'fight' (I am not sure about this - if you are sure you should believe this answer much more).
'carried' means one lot of letters goes inside another.
'about' becomes 're' ('re' means regarding or about).
'fight' enclosing 're' is 'FREIGHT'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for freight that I've seen before include "Something carried" , "Goods carries by large vehicle" , "Commercial transport" , "Goods in transit" , "Cargo, goods transported" .)