Peak Practice's opening leads to popular, clean broadcast (8)
I believe the answer is:
pinnacle
'peak' is the definition.
(pinnacle is a kind of peak)
'practice's opening leads to popular clean broadcast' is the wordplay.
'opening' indicates taking the first letters.
'leads' means one lot of letters go next to another.
'to popular' becomes 'in'.
'broadcast' indicates an anagram.
The initial letter of 'practices' is 'p'.
'clean' is an anagram of 'nacle'.
'p'+'in'+'nacle'='PINNACLE'
(Other definitions for pinnacle that I've seen before include "Topmost point" , "Culmination" , "Crown" , "Apogee" , "Towering peak" .)