The most common and most likely answer to this crossword clue is the 3 plus 6 letter word TOM SAWYER
I've seen this crossword clue in Financial Times
T
O
M
S
A
W
Y
E
R
More clues leading to the result TOM SAWYER
- Mayor associated with wets - sadly he was infatuated with Thatcher
- Literary hero’s cat spotted you by river
- Literary hero some way misrepresented in first couple of translations
- Twain boy most upset by solicitor dropping line
- Adventurous boy ate worms wriggling around yard
- Boy hero involved in steamy row
- Adventurous American boy reported to Lady Godiva?
- Adventurous boy from Surrey was motivated to return
- One avoiding complete whitewash in fencing discipline
- You were spotted by eavesdropper, we hear — lad seeking adventure
Buddy explains!
The straight part
We know that "Boy hero" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case boy hero = tom sawyer.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.