The most common and most likely answer to this crossword clue is the 6 plus 6 letter word RAZZLE DAZZLE
I've seen this crossword clue in The Guardian
R
A
Z
Z
L
E
D
A
Z
Z
L
E
Buddy explains!
The straight part
We know that "song from Chicago" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case song from chicago = razzle dazzle.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.
What does RAZZLE DAZZLE mean?
RAZZLE DAZZLE noun- Glitz, glamor/glamour, showiness, or pizazz.
- Dazzle camouflage
- To confuse or overcome with glamour or showiness; to dazzle.