Stone used in a large monolith (3)

I believe the answer is:

gem

'stone' is the definition.
(thesaurus)

'in a large monolith' is the wordplay.
'in' indicates a hidden word.
'GEM' can be found hidden inside 'large monolith'.

'used' is the link.

(Other definitions for gem that I've seen before include "Diamond, ruby, or emerald" , "Valuable stone" , "Emerald or sapphire, say" , "Treasured person" , "Valued person; jewel" .)

I've seen this clue in the Evening Standard.

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