Defeat; throb (4)
I believe the answer is:
beat
I believe this clue is a double definition.
'defeat' is the first definition.
(I know that beat is a more specific form of defeat)
'throb' is the second definition.
(I know that throb is a more specific form of beat)
(Other definitions for beat that I've seen before include "Baffle - all in" , "course run regularly" , "Rhythm, stir vigorously" , "Thrash, punish physically" , "Thrash; pulse" .)