The most common and most likely answer to this crossword clue is the 3 plus 4 plus 4 letter word ALL THAT JAZZ
I've seen this crossword clue in Independent
A
L
L
T
H
A
T
J
A
Z
Z
Buddy explains!
The straight part
We know that "The output of 23 16 26 11 et al and such stuff" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the output of 23 16 26 11 et al and such stuff = all that jazz.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.