A component of copper, for example (7)
I believe the answer is:
element
I believe this is a double definition.
'a component' is the first definition.
('element' can be a synonym of 'component')
'copper for example' is the second definition.
(copper is a kind of element)
'of' is the link.
(Other definitions for element that I've seen before include "A first principle, found in a kettle?" , "Wire in electric fire" , "piece" , "Ideal situation for someone" , "He or I maybe" .)