The most common and most likely answer to this crossword clue is the 7 letter word REACHER
I've seen this crossword clue in The Guardian
R
E
A
C
H
E
R
More clues leading to the result REACHER
Buddy explains!
The straight part
We know that "Child’s hero" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case child’s hero = reacher.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 REACHER mean?
REACHER noun- A person who reaches.
- A device used to reach something.
- A sail, a kind of asymmetrical spinnaker.
- An exaggeration.