Freight from cape on Jason's boat (5)
I believe the answer is:
cargo
'freight' is the definition.
(synonyms)
'cape on jason's boat' is the wordplay.
'cape' becomes 'c' (abbreviation used on maps).
'on' means one lot of letters go next to another.
'jason's boat' becomes 'argo' (I've seen this before).
'c'+'argo'='CARGO'
'from' acts as a link.
(Other definitions for cargo that I've seen before include "Goods carried by ship, aircraft" , "Payload" , "Consignment" , "Load carried" , "Goods carried by a large vehicle" .)