Strange about a king turning into stone (10)
I believe the answer is:
remarkable
'strange' is the definition.
(thesaurus)
'about a king turning into stone' is the wordplay.
I cannot quite understand how this works, but
'about' could be 're' (regarding) and 're' is present in the answer.
'a' is present in the answer.
'king' could be 'r' (r is abbreviation for rex) and 'r' is found within the answer.
This explanation may well be incorrect...
(Other definitions for remarkable that I've seen before include "A wrongly-graded exam paper" , "Noteworthy" , "unusual" , "Extraordinary" , "Striking" .)