Say titanium piece (7)
I believe the answer is:
element
This clue is a double definition.
'say titanium' is the first definition.
(I know that Titanium is a single)
'piece' is the second definition.
(I've seen this before)
(Other definitions for element that I've seen before include "that's used in heating" , "eg Fire, air" , "lead, for example" , "An abstract part of something" , "Wire in electric fire" .)