The most common and most likely answer to this crossword clue is the 7 letter word KACHINA
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Buddy explains!
The straight part
We know that "One of the ancestral spirits" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one of the ancestral spirits = kachina.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 KACHINA mean?
KACHINA noun- (Pueblo culture) A vaguely ancestral anthropomorphic spirit being, associated with clouds and rain or personifying the power in the sun, the earth or corn (among other things).
- (Pueblo culture) A wooden doll, as might be given to a child, which represents such a being.
- (Pueblo culture) A masked dancer who represents such a being in a ceremonial dance or masked ceremony.