The most common and most likely answer to this crossword clue is the 9 letter word DEFICIENT
I've seen this crossword clue in Financial Times
D
E
F
I
C
I
E
N
T
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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 DEFICIENT mean?
DEFICIENT adjective- Lacking something essential; often construed with in.
- Insufficient or inadequate in amount.
- Of a number n, Having the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n)