Defeats a wild beast (5)
I believe the answer is:
beats
'defeats' is the definition.
('beat' can be a synonym of 'defeat')
'a wild beast' is the wordplay.
'a wild' is an anagram indicator.
'beast' is an anagram of 'BEATS'.
(Other definitions for beats that I've seen before include "Regular routes for policemen" , "Tans" , "Buffets" , "Rhythms" .)