Beaten lad upset jockeys (8)
I believe the answer is:
pulsated
'beaten' is the definition.
(pulsating is a kind of beating)
'lad upset jockeys' is the wordplay.
'jockeys' is an anagram indicator.
'lad'+'upset'='ladupset'
'ladupset' anagrammed gives 'PULSATED'.
(Other definitions for pulsated that I've seen before include "Throbbed, expanded and contracted rhythmically" , "Beat" , "Thrilled" .)