Type of chair (5)
I believe the answer is:
'type of chair' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sedan that I've seen before include "Type of chair that's carried" , "Type of chair - battle" , "Chair used as transport" , "Once a mobile chair for Danes" , "Covered seat carried by bearers" .)