Disconnect one French piano to carry (6)
I believe the answer is:
unplug
'disconnect' is the definition.
(I know that disconnect can be written as unplug)
'one french piano to carry' is the wordplay.
'one french' becomes 'un' ('one' in French).
'piano' becomes 'p' (musical abbreviation).
'to carry' becomes 'lug' (lug can mean to carry).
'un'+'p'+'lug'='UNPLUG'
(Other definitions for unplug that I've seen before include "Remove from a socket" , "Remove power from" , "Disconnect from power" , "Take out of socket" , "Disconnect (kettle or toaster?)" .)