Concluding premiere of show’s excellent (8)
I believe the answer is:
stopping
'concluding premiere' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'of show's excellent' is the wordplay.
'of show' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'excellent' becomes 'topping' (I've seen this before).
's'+'topping'='STOPPING'
Can you help me to learn more?
(Other definitions for stopping that I've seen before include "Blocking; ceasing" , "Taking a break" , "Halting" , "Prevention" .)