Hearing, once again, trailer being broadcast (7)
I believe the answer is:
retrial
'hearing once again' is the definition.
'retrial' can be an answer for 'hearing' (I have seen 'Further hearing ' mean 'retrial' so perhaps 'hearing' could also mean 'retrial'). I'm not sure about the 'once again' bit.
'trailer being broadcast' is the wordplay.
'being broadcast' indicates an anagram (letters scattered or cast around).
'trailer' with letters rearranged gives 'RETRIAL'.
Can you help me to learn more?
(Other definitions for retrial that I've seen before include "Revived case" , "Further action" , "Second court hearing" , "Hearing repeat" , "test, after failure in first" .)