Some gent renovated jewel (8)
I believe the answer is:
gemstone
'jewel' is the definition.
(I've seen this before)
'some gent renovated' is the wordplay.
'renovated' is an anagram indicator.
'some'+'gent'='somegent'
'somegent' anagrammed gives 'GEMSTONE'.
(Other definitions for gemstone that I've seen before include "Sparkler" , "Eg, sapphire" , "Jewel" , "something of great value" , "[RUBY] , for example" .)