Ordinary type of transport discussed (5)
I believe the answer is:
plain
'ordinary' is the definition.
(I've seen this before)
'type of transport discussed' is the wordplay.
'type of transport' becomes 'plane'.
'discussed' shows a homophone (sound like).
'plane' sounds like 'PLAIN'.
(Other definitions for plain that I've seen before include "Unadorned; evident" , "not striking" , "Simple, unadorned" , "Clear - open - grassland" , "Treeless expanse" .)