Disciplinarian, martinet (8)
I believe the answer is:
stickler
I believe this is a double definition.
'disciplinarian' is the first definition.
(I know that stickler is a type of disciplinarian)
'martinet' is the second definition.
(I know that stickler is a type of martinet)
(Other definitions for stickler that I've seen before include "Perfectionist" , "Pernickety person" , "Trickles for someone who insists" , "Nit-picker" , "Someone who insists on something" .)