Talk about port vehicle (7)
I believe the answer is:
chariot
'vehicle' is the definition.
(I know that chariot is a type of military vehicle)
'talk about port' is the wordplay.
'talk' becomes 'chat' (chat can mean to talk).
'about' means one lot of letters goes inside another.
'port' becomes 'rio' (Rio de Janeiro is a port).
'chat' going around 'rio' is 'CHARIOT'.
(Other definitions for chariot that I've seen before include "ceremonial carriage" , "Two-wheeled carriage of ancient times, as used by Ben Hur" , "Vehicle in Ben Hur?" , "ride in carriage" , "Old vehicle (of fire?)" .)