Container to transport in advance (6)
I believe the answer is:
carton
'container' is the definition.
(carton is a kind of container)
'transport in advance' is the wordplay.
'transport' becomes 'cart' (cart is a kind of transport).
'in advance' becomes 'on' (I've seen this in other clues).
'cart'+'on'='CARTON'
'to' is the link.
(Other definitions for carton that I've seen before include "Cardboard or plastic container" , "Box made of cardboard" , "A cardboard container as for milk" , "Box without great strength" , "Flapped cardboard box" .)