Came across aluminium, and titanium, for example (5)
I believe the answer is:
metal
'titanium for example' is the definition.
(titanium is a kind of metal)
'came across aluminium' is the wordplay.
'came across' becomes 'met' ('meet' can be a synonym of 'come across').
'aluminium' becomes 'al' ('Al' can be a synonym of 'aluminium').
'met'+'al'='METAL'
'and' is the link.
(Other definitions for metal that I've seen before include "Aluminium or copper for instance" , "Eg, copper" , "Eg, Iron or gold" , "Element eg for road or rail" , "Musically it can be heavy" .)