Conveyance's surface (5)
I believe the answer is:
plane
I believe this is a double definition.
'conveyance's' is the first definition.
(plane is a kind of conveyance)
'surface' is the second definition.
(thesaurus)
(Other definitions for plane that I've seen before include "Nepal (anag.)" , "Smooth" , "What imitates bird" , "Aircraft - level surface - carpenter's tool" , "Woodworker's tool" .)