Current carrying master switch for conductors (7)
I believe the answer is:
maestri
'conductors' is the definition.
(I've seen this before)
'current carrying master switch' is the wordplay.
'current' becomes 'i' (symbol for electric current).
'carrying' is a charade indicator (letters next to each other) (in a down clue, the bottom letters carry others).
'switch' indicates anagramming the letters.
'master' anagrammed gives 'maestr'.
'i' put after 'maestr' is 'MAESTRI'.
'for' acts as a link.
(Other definitions for maestri that I've seen before include "Eminent musical conductors" , "Distinguished conductors" , "masters" , "Experts" , "Top conductors" .)