Chosen way, do we hear, to become a conductor (9)
I believe the answer is:
electrode
'a conductor' is the definition.
(I know that electrode is a type of conductor)
'chosen way do we hear' is the wordplay.
'chosen' becomes 'elect' ('elect' as an adjective can mean chosen).
'way' becomes 'road' (road is a kind of way).
'do we hear' indicates a 'sounds like' (homophone) clue.
'road' sounds like 'rode'.
'elect'+'rode'='ELECTRODE'
'to become' acts as a link.
(Other definitions for electrode that I've seen before include "Conducting contact" , "Conductor (eg, in battery)" , "Conducting point by which electric current enters or leaves" , "Connecting conductor" , "Conducting terminal" .)