Plod's correct about Director-General! (6)
I believe the answer is:
trudge
'plod's' is the definition.
('trudge' can be a synonym of 'plod')
'correct about director-general' is the wordplay.
'correct' becomes 'true' ('true' is associated in meaning with 'correct').
'about' indicates putting letters inside.
'director-general' becomes 'dg' (common abbreviation).
'true' enclosing 'dg' is 'TRUDGE'.
(Other definitions for trudge that I've seen before include "Walk heavily or laboriously" , "tramp" , "March joylessly" , "Plod doggedly" , "Walk wearily" .)