The most common and most likely answer to this crossword clue is the 4 letter word CIST
C
I
S
T
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The straight part
We know that "a ritual implements box?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a ritual implements box? = cist.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 CIST mean?
CIST noun- A small receptacle for sacred utensils carried in festivals in Ancient Greece.
- A crypt cut into rock, chalk, or a tree trunk, especially a coffin formed by placing stone slabs on edge and topping them with a horizontal slab or slabs.