The most common and most likely answer to this crossword clue is the 10 letter word PLANCHETTE
P
L
A
N
C
H
E
T
T
E
Buddy explains!
The straight part
We know that "One supposedly helping to spell message from above" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one supposedly helping to spell message from above = planchette.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 PLANCHETTE mean?
PLANCHETTE noun- A small plank.
- A type of Ouija board. (A small tablet of wood supported on casters and having a pencil attached. The characters produced by the pencil on paper, while the hand rests on the instrument and it is allowed to move, are sometimes interpreted as of oracular or supernatural import.)
- A plane table.
- One of the round colored dots pressed into paper money, used to distinguish authentic currency from counterfeit currency.