The most common and most likely answer to this crossword clue is the 12 letter word UNIDENTIFIED
U
N
I
D
E
N
T
I
F
I
E
D
Buddy explains!
The straight part
We know that "not recognised" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not recognised = unidentified.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 UNIDENTIFIED mean?
UNIDENTIFIED adjective- Not identified; having an unknown or unnamed identity.