Recording's about to fail, admitting of no further discussion (6)
I believe the answer is:
closed
'admitting of no further discussion' is the definition.
I can't tell whether this defines the answer.
'recording's about to fail' is the wordplay.
'recording' becomes 'CD' (type of recording).
'about' means one lot of letters goes inside another.
'to fail' becomes 'lose' (I've seen this in another clue).
'cd' enclosing 'lose' is 'CLOSED'.
Can you help me to learn more?
(Other definitions for closed that I've seen before include "Terminated" , "Concluded or fastened" , "restricted" , "Exclusive" , "Held in private" .)