Dogmatic rambling in a director (11)
I believe the answer is:
doctrinaire
'dogmatic' is the definition.
(thesaurus)
'rambling in a director' is the wordplay.
'rambling' indicates anagramming the letters.
'in'+'a'+'director'='inadirector'
'inadirector' with letters rearranged gives 'DOCTRINAIRE'.
(Other definitions for doctrinaire that I've seen before include "Impractical theorist" , "Dogmatic" , "Seeking to impose a view" , "not practical" , "Inclined to follow principles to unworkable extremes" .)