One perhaps turned to stone (8)
I believe the answer is:
sapphire
'stone' is the definition.
(thesaurus)
'one perhaps turned' is the wordplay.
'one' becomes 'i' (Roman numeral).
'turned' indicates an anagram.
'i'+'perhaps'='iperhaps'
'iperhaps' with letters rearranged gives 'SAPPHIRE'.
'to' is the link.
(Other definitions for sapphire that I've seen before include "Precious transparent stone of blue corundum" , "His paper can be turned into a jewel" , "precious item" , "Blue gemstone" , "His paper can be made into a jewel" .)