Beast of burden turned everyone against master (5)
I believe the answer is:
llama
'beast of burden' is the definition.
(I've seen this before)
'turned everyone against master' is the wordplay.
'turned' is a reversal indicator.
'everyone' becomes 'all' (all people).
'against' says to put letters next to each other.
'master' becomes 'ma' (Master of Arts).
'all' back-to-front is 'lla'.
'lla'+'ma'='LLAMA'
(Other definitions for llama that I've seen before include "20vian beast" , "mammal that chews cud" , "Andean beast of burden" , "South American animal of the camel family" , "South American native" .)