Military plane gets engineers from cargo ship (9)
I believe the answer is:
freighter
'cargo ship' is the definition.
(freighter is a kind of cargo ship)
'military plane gets engineers' is the wordplay.
'military plane' becomes 'fighter'.
'gets' means one lot of letters goes inside another (gets can mean captures or absorbs).
'engineers' becomes 're' (Royal Engineers).
'fighter' enclosing 're' is 'FREIGHTER'.
'from' acts as a link.
(Other definitions for freighter that I've seen before include "Cargo-ship" , "Cargo-carrying ship or plane" , "Cargo ship" , "transport vessel" , "A plane carrying large load" .)