Runner in drama to stir cast (13)
I believe the answer is:
administrator
'runner' is the definition.
(someone who runs things)
'in drama to stir cast' is the wordplay.
'cast' indicates an anagram (letters are dispersed or cast around).
'in'+'drama'+'to'+'stir'='indramatostir'
'indramatostir' with letters rearranged gives 'ADMINISTRATOR'.
(Other definitions for administrator that I've seen before include "I'll manage" , "one controls" , "One who manages an organisation" , "Official organiser" , "Manager, controller" .)