Vote for Hull ensemble's lead conductor (9)
I believe the answer is:
electrode
'conductor' is the definition.
(electrode is a kind of conductor)
'vote for hull ensemble's lead' is the wordplay.
'vote for' becomes 'elect' (vote for in an election).
'hull' becomes 'rod' (I can't explain this - if you can you should give a lot more credence to this answer).
'lead' suggests taking the first letters.
The initial letter of 'ensembles' is 'e'.
'elect'+'rod'+'e'='ELECTRODE'
Can you help me to learn more?
(Other definitions for electrode that I've seen before include "Conducting terminal" , "Conducting point by which electric current enters or leaves" , "Conductor making contact in a circuit" , "Conducting contact" , "Conductor for electricity as it enters or leaves" .)