Carriage sounds cheap (4)
I believe the answer is:
mien
'carriage' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mien that I've seen before include "Air - look - manner" , "Facial expression sounds miserly" , "Appearance is strangely mine" , "Bearing, demeanour" , "A manner like mine" .)