Old racer having discussion about former Olympic hosts (7)
I believe the answer is:
chariot
'old racer' is the definition.
'discussion about former olympic hosts' is the wordplay.
'discussion' becomes 'chat'.
'about' means one lot of letters goes inside another.
'former olympic hosts' becomes 'rio'.
'chat' enclosing 'rio' is 'CHARIOT'.
'having' is the link.
(Other definitions for chariot that I've seen before include "Horse-drawn racing vehicle; oat rich (anag.)" , "Two-wheeled carriage of ancient times, as used by Ben Hur" , "Two-wheeled horse-drawn vehicle used in battle" , "Ben Hur transport?" , "coach" .)