One reinstated in the team? (4)
I believe the answer is:
'one' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for back that I've seen before include "Help!" , "Place where secret deals are done" , "Support; footballer" , "part of the body" , "Fashionable again" .)