Effect of current conductor having left in minutes (9)
I believe the answer is:
maelstrom
'effect of current' is the definition.
'conductor having left in minutes' is the wordplay.
'conductor' becomes 'maestro' (I've seen this before).
'having' means one lot of letters goes inside another.
'left in' becomes 'l' (I've seen this in other clues).
'minutes' becomes 'm'.
'maestro' placed around 'l' is 'maelstro'.
'maelstro'+'m'='MAELSTROM'
(Other definitions for maelstrom that I've seen before include "Confused situation" , "Powerful circular current of water" , "fearsome current" , "confused state of affairs" , "danger to shipping" .)