Assume trios, once played, will provide what you want to hear (5,2,4,4)
I believe the answer is:
music to ones ears
'what you want to hear' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'assume trios once played' is the wordplay.
'played' is an anagram indicator.
'assume'+'trios'+'once'='assumetriosonce'
'assumetriosonce' is an anagram of 'MUSIC TO ONES EARS'.
'will provide' acts as a link.
Can you help me to learn more?
(Other definitions for music to ones ears that I've seen before include "what travels at a pop festival, say" , "Radio 3 output" , "excellent news" , "report of some art?" , "news that's very welcome" .)