The most common and most likely answer to this crossword clue is the 5 plus 3 letter word STRUT ONE
I've seen this crossword clue in The Daily Telegraph
S
T
R
U
T
O
N
E
Buddy explains!
The straight part
We know that "Dance/show off" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dance/show off = strut one.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.