Ersatz swing (4)
I believe the answer is:
tire
'ersatz swing' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tire that I've seen before include "one of four found on Chevrolet?" , "Grow weary of rithe" , "Become exhausted" , "Weaken" , "Grow weary of rite" .)