Mixture or alloy (8)
I believe the answer is:
compound
I believe this clue is a double definition.
'mixture' is the first definition.
(thesaurus)
'alloy' is the second definition.
(thesaurus)
(Other definitions for compound that I've seen before include "Add on to" , "See 10" , "Make worse; property enclosure" , "Exacerbate; pen" , "In this fracture, bone has pierced the skin" .)