Defeats pulses (5)
I believe the answer is:
beats
I believe this clue is a double definition.
'defeats' is the first definition.
('beat' can be a synonym of 'defeat')
'pulses' is the second definition.
('beat' can be a synonym of 'pulse')
(Other definitions for beats that I've seen before include "Regular routes for policemen" , "Tans" , "Rhythms" , "Buffets" .)