Maybe jet set gnome corrupted (8)
I believe the answer is:
gemstone
'maybe jet' is the definition.
(I know that jet is a type of gemstone)
'set gnome corrupted' is the wordplay.
'corrupted' is an anagram indicator.
'set'+'gnome'='setgnome'
'setgnome' anagrammed gives 'GEMSTONE'.
(Other definitions for gemstone that I've seen before include "Emerald or ruby" , "something of great value" , "Sparkler" , "Eg, sapphire" , "Piece of crystalline rock as jewellery" .)