Rock night broadcast, with Yes playing first (7)
I believe the answer is:
syenite
'rock night' is the definition.
'syenite' can be an answer for 'rock' (type of igneous rock). I'm not certain of the 'night' bit.
'broadcast with yes playing first' is the wordplay.
'broadcast with' becomes 'nite' (I can't explain this - if you can you should give a lot more credence to this answer).
'playing' indicates anagramming the letters.
'first' says to put letters next to each other.
'yes' is an anagram of 'sye'.
'nite' put after 'sye' is 'SYENITE'.
Can you help me to learn more?
(Another definition for syenite that I've seen is " rock".)