The most common and most likely answer to this crossword clue is the 15 letter word RUMPELSTILTSKIN
I've seen this crossword clue in Financial Times
R
U
M
P
E
L
S
T
I
L
T
S
K
I
N
More clues leading to the result RUMPELSTILTSKIN
- Dwarf with odd skin mostly raises family
- Bottom golfer leans on family to get secret identity?
- First to read new Little Miss Punk children’s book
- In children’s story, strange pets still disturbed family
- Impish type cast its spellin weird family
- Fairy tale character remains on the Spanish circus apparatus with family
- Golfer lists family members following behind imp and trickster
- Bully kills strumpet, popular and impish creature
- Legendary spinner in Trump kiss and tell broadcast
- Bottom golfer jousts with relations, one of little stature
Buddy explains!
The straight part
We know that "secret identity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case secret identity = rumpelstiltskin.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.