Humour ultimately missing from sadly integral part of a joke? (3,4)
I believe the answer is:
tag line
'part of a joke?' is the definition.
('tag line' is part of 'joke')
'humour ultimately missing from sadly integral' is the wordplay.
I cannot really see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tag line that I've seen before include "Slogan" , "Something memorable one might say" , "End of joke" , "Catchphrase (mainly US)" .)