Reflection of petrifying monster would show no such spirit (4)

I believe the answer is:

grog

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'spirit' is the definition.
(I know that grog is a type of rum)

I don't understand how the rest of the clue works.

(Other definitions for grog that I've seen before include "Old sailors' tipple" , "Traditional naval drink" , "Rum mixed with water" , "Sailors' drink of rum and water" , "Drink of spirits and water liked by sailors" .)

I've seen this clue in The Times.

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