Tuned in to On The Ball (5)
I believe the answer is:
aware
This clue might be a double definition.
'tuned' is the first definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?
'to on the ball' is the second definition.
(thesaurus)
'in' is the link.
Can you help me to learn more?
(Other definitions for aware that I've seen before include "Bearing in mind" , "Alert, conscious of" , "Apprised or informed" , "well informed" , "Acquainted with or conscious of" .)