Finishes off joke in music hall show not needing to be cracked? (2,5)
I believe the answer is:
en clair
'not needing to be cracked?' is the definition.
(en clair means not in code)
'finishes off joke in music hall show' is the wordplay.
'finishes off' suggests the final letters (take the finishing letters off of the words).
'show' becomes 'air' (both can mean broadcast).
The final letters of 'joke in music hall' are 'encl'.
'encl'+'air'='EN CLAIR'
(Other definitions for en clair that I've seen before include "in the Open" , "not coded" , "N ot in code/cipher" , "Not in cipher" , "Not in code or cypher" .)