Conductor making return went by bus? (9)
I believe the answer is:
electrode
'conductor' is the definition.
(I know that electrode is a type of conductor)
'return went by bus?' is the wordplay.
'return' becomes 'elect' (I've seen this before).
'went by bus?' becomes 'rode' (I've seen this in another clue).
'elect'+'rode'='ELECTRODE'
'making' acts as a link.
(Other definitions for electrode that I've seen before include "Terminal of, eg, an acid battery" , "Conducting contact" , "Conductor (eg, in battery)" , "Conducting terminal" , "Conductor making contact in a circuit" .)