The most common and most likely answer to this crossword clue is the 8 letter word FACELESS
I've seen this crossword clue in Financial Times
F
A
C
E
L
E
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S
More clues leading to the result FACELESS
Buddy explains!

The straight part
We know that "Unidentifiable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unidentifiable = faceless.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 FACELESS mean?
FACELESS adjective- Having no face
- Having or revealing no individual identity or character; anonymous.
- Having or revealing no individuality, personality or distinctive characteristics.