Conductor will choose the right verse (9)
I believe the answer is:
electrode
'conductor' is the definition.
(electrode is a kind of conductor)
'will choose the right verse' is the wordplay.
'will' means one lot of letters go next to another (I've seen this in other clues).
'choose' becomes 'elect' (electing is a kind of choosing**).
'the right' becomes 'r' (common abbreviation).
'verse' becomes 'ode'.
'elect' put next to 'r' is 'electr'.
'electr'+'ode'='ELECTRODE'
(Other definitions for electrode that I've seen before include "Conducting point by which electric current enters or leaves" , "Conductor by which current enters" , "Conducting contact" , "Conductor (eg, in battery)" , "Connecting conductor" .)