The beaters disturbed an antelope (10)
I believe the answer is:
hartebeest
'an antelope' is the definition.
(I know that hartebeest is a type of antelope)
'the beaters disturbed' is the wordplay.
'disturbed' indicates an anagram (the order of letters is disturbed).
'the'+'beaters'='thebeaters'
'thebeaters' anagrammed gives 'HARTEBEEST'.
(Other definitions for hartebeest that I've seen before include "antelope" , "Game" , "wild animal" , "African native" , "Creature" .)