Previous champion (4)
I believe the answer is:
back
This might be a double definition.
'previous' is the first definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I don't see?
'champion' is the second definition.
(both can mean to endorse or support)
Can you help me to learn more?
(Other definitions for back that I've seen before include "Support a play - player" , "Support - defender - reverse" , "Second" , "defensive player" , "Support - football player" .)