The most common and most likely answer to this crossword clue is the 10 letter word GOLDILOCKS
I've seen this crossword clue in The Guardian
G
O
L
D
I
L
O
C
K
S
More clues leading to the result GOLDILOCKS
- Valuable metal one keeps secure for blonde
- Crazy dog kills old Charlie character in nursery story
- Wealth is about to provide security for girl in panto
- One who confronted 7s with rifles, protecting elderly setter
- Wealth is about to provide security for a girl in nursery story
- Fairy-tale character I left in clip? Hard work’s over including it
- Bullion is secure inside plant
- Grand veteran one imprisons: she got several tastes of porridge
- Soldier guarding antique provides security for heroine
Buddy explains!

The straight part
We know that "character in nursery story" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case character in nursery story = goldilocks.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 GOLDILOCKS mean?
GOLDILOCKS noun- A person with golden hair, especially a girl with long hair.
- A goldilocks aster, Aster linosyris.