Machine part in America matched (3)
I believe the answer is:
cam
'machine part' is the definition.
(I've seen this in another clue)
'in america matched' is the wordplay.
'in' indicates the answer is hidden within the clue.
'CAM' can be found hidden inside 'america matched'.
(Other definitions for cam that I've seen before include "Shaft on a rotating part in machinery" , "Reciprocal-motion part" , "Projection on rotating shaft imparting motion" , "River of eastern England" , "Bump on a shaft for pushing another shaft" .)