Troops didn't finish the course (7)
I believe the answer is:
regimen
'the course' is the definition.
(I've seen this before)
'troops didn't finish' is the wordplay.
I cannot really understand how this works, but
'troops' could be 'men' (men can mean soldiers) and 'men' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for regimen that I've seen before include "Method of working" , "Government - course of treatment" , "recommended diet" , "Prescribed course of diet, exercise, etc" , "Disciplined system" .)