The most common and most likely answer to this crossword clue is the 9 plus 6 letter word HENRYÂ THE FOURTH
I've seen this crossword clue in The Guardian
H
E
N
R
Y
Â
T
H
E
F
O
U
R
T
H
Buddy explains!
The straight part
We know that "Leading man that has two parts on stage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case leading man that has two parts on stage = henry the fourth.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.