Troublemaker’s air got at cast (8)
I believe the answer is:
agitator
'troublemaker's' is the definition.
(agitator is a kind of troublemaker)
'air got at cast' is the wordplay.
'cast' indicates an anagram (letters are dispersed or cast around).
'air'+'got'+'at'='airgotat'
'airgotat' with letters rearranged gives 'AGITATOR'.
(Other definitions for agitator that I've seen before include "One stirring up (things)" , "Organiser" , "A mover and shaker - or troublemaker" , "Demagogue" , "washing machine" .)