As a concert piece, it can't fail (4)
I believe the answer is:
'it can't fail' is the definition.
The definition suggests a singular noun which matches the answer.
'as a concert piece' is the wordplay.
'CERT' is hidden in amongst the letters.
But, I am uncertain how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for cert that I've seen before include "Classification" , "Inevitable event" , "One sure to win (slang)" , "Sure thing (that could be dead!)" , "Sure thing, in short" .)