Sport's nine sides to be announced by league repeatedly (7)
I believe the answer is:
netball
'sport's' is the definition.
(netball is a sport)
'nine sides to be announced by league repeatedly' is the wordplay.
'sides' suggests removing the centre (only the letters on the sides are used).
'to be announced' becomes 'tba' (this might be a standard abbreviation of which I'm unaware).
'by' is a charade indicator (letters next to each other).
'league' becomes 'l' (abbreviation).
'repeatedly' indicates the doubling of some letters.
'nine' with its centre taken out is 'ne'.
'l' duplicated is 'll'.
'ne'+'tba'+'ll'='NETBALL'
Can you help me to learn more?
(Other definitions for netball that I've seen before include "activity no longer associated solely with girls" , "Team game for tall Ben" , "Sport whose players wear bibs" , "Team game, played mainly by women" , "Seven-a-side team game -- all bent (anag)" .)