Conductor’s chosen baton perhaps used with energy (9)
I believe the answer is:
electrode
'conductor's' is the definition.
(electrode is a kind of conductor)
'chosen baton perhaps used with energy' is the wordplay.
'chosen' becomes 'elect' ('elect' as an adjective can mean chosen).
'baton perhaps' becomes 'rod' (baton is a kind of rod).
'used with' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mc2).
'elect'+'rod'+'e'='ELECTRODE'
(Other definitions for electrode that I've seen before include "Connecting conductor" , "Conducting contact" , "Conducting point by which electric current enters or leaves" , "Terminal of, eg, an acid battery" , "Conductor by which current enters" .)