For example, copper kettle contains this (7)
I believe the answer is:
element
'for example copper' is the definition.
(copper is a chemical element)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for element that I've seen before include "part of a toaster" , "Eg copper" , "Fire (or part of one)" , "that's used in heating" , "Fundamental component" .)