The most common and most likely answer to this crossword clue is the 10 letter word ACCUSATIVE
I've seen this crossword clue in The Daily Telegraph
A
C
C
U
S
A
T
I
V
E
Buddy explains!
The straight part
We know that "case" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case case = accusative.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 ACCUSATIVE mean?
ACCUSATIVE noun- (grammar) The accusative case.
- Producing accusations; in a manner that reflects a finding of fault or blame
- (grammar) Applied to the case (as the fourth case of Latin, Lithuanian and Greek nouns) which expresses the immediate object on which the action or influence of a transitive verb has its limited influence. Other parts of speech, including secondary or predicate direct objects, will also influence a sentence’s construction. In German the case used for direct objects.