Crossword Genius

Disney movie doesn’t end up in compound (4)

Ross

I believe the answer is:

alum

I'm a little stuck... Click here to teach me more about this clue!

'compound' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for alum that I've seen before include "Sulphate; maul (anag.)" , "White mineral salt used in medicine and in dyeing" , "Potassium compound; IoW sandy bay" , "Name given to a specific chemical compound and a class of them" , "double sulphate" .)

I've seen this clue in The Hindu.
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