Strict disciplinarian (8)
I believe the answer is:
martinet
'strict disciplinarian' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for martinet that I've seen before include "Trite man becomes a tyrant" , "A strict disciplarian" , "A rigorous operator" , "drillmaster" , "Rigorous figure" .)