Be defeated (4)
'be defeated' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lose that I've seen before include "Fail to keep" , "Be beaten" , "Cease to have" , "Suffer a defeat" , "Shake off (a pursuer)" .)
(Other definitions for bite the dust that I've seen before include "getting soiled teeth?" , "Completely fail; die" , "Perish" , "Fall badly" , "Fall down dead" .)