The most common and most likely answer to this crossword clue is the 6 plus 3 plus 6 letter word TREADS THE BOARDS
T
R
E
A
D
S
T
H
E
B
O
A
R
D
S
Buddy explains!
The straight part
We know that "goes on stage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case goes on stage = treads the boards.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.