Piece of trim in Italian car (4)
I believe the answer is:
mini
'car' is the definition.
(Mini Cooper)
'piece of trim in italian' is the wordplay.
'piece of' says the answer is hidden in the clue.
'MINI' is hidden in the letters of 'trim in italian'.
(Other definitions for mini that I've seen before include "type of garment" , "Short skirt - small car" , "Once fashionable skirt" , "Car; short dress" , "(Car etc) of small size" .)