The most common and most likely answer to this crossword clue is the 11 letter word PROTAGONIST
I've seen this crossword clue in The Daily Telegraph
P
R
O
T
A
G
O
N
I
S
T
More clues leading to the result PROTAGONIST
- Lead giant troops astray
- Go into parts designed for leading character
- Leading player waving to organist after start of pastorale
- Star of ‘Argo’ isn’t top unfortunately
- Star in spot orating terribly
- Star part, so got in cast
- Leading light in the past isn’t prepared to follow etiquette
- Recast, so got part in title role
- Patriot song composed for champion
- Lead part, so got in cast
Buddy explains!

The straight part
We know that "leading character" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case leading character = protagonist.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 PROTAGONIST mean?
PROTAGONIST noun- (authorship) The main character, or one of the main characters, in any story, such as a literary work or drama.
- A leading person in a contest; a principal performer.
- An advocate or champion of a cause or course of action.