Range, note, is marble (5)
I believe the answer is:
agate
'is marble' is the definition.
(thesaurus)
'range note' is the wordplay.
'range' becomes 'aga' (I've seen this before).
'note' becomes 'te' (**).
'aga'+'te'='AGATE'
(Other definitions for agate that I've seen before include "On the way" , "Onyx" , "Semi-precious stone" , "Semi-transparent stone" , "Old drama critic" .)