The most common and most likely answer to this crossword clue is the 6 letter word GRAILS
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The straight part
We know that "chalices" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chalices = grails.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 GRAILS mean?
GRAILS noun- The Holy Grail.
- The object of an extended or difficult quest.http//www.merriam-webster.com/dictionary/grail
- A book of offices in the Roman Catholic Church; a gradual.
- One of the small feathers of a hawk.