The most common and most likely answer to this crossword clue is the 9 letter word ADNOMINAL
I've seen this crossword clue in The Guardian
A
D
N
O
M
I
N
A
L
More clues leading to the result ADNOMINAL
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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 ADNOMINAL mean?
ADNOMINAL adjective- (grammar) Of or pertaining to an adnoun.
- (grammar) A word or phrase qualifying a noun, such as an adjective or a relative clause.
- (grammar) Involving or relating to words that modify a noun.