Turning a person to rock! (5)

I believe the answer is:

stone

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'to rock' is the definition.
(synonyms)

'turning a person' is the wordplay.
'turning' becomes 'st' (I am not sure about this - if you are sure you should believe this answer much more).
'a person' becomes 'one' (an individual).
'st'+'one'='STONE'

Can you help me to learn more?

(Other definitions for stone that I've seen before include "Pebble" , "Piece of rock - weight" , "See 19" , "diamond, say" , "Seed of e.g. cherry" .)

I've seen this clue in the Evening Standard.

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