Soldiers don't finish course (7)
I believe the answer is:
regimen
'course' is the definition.
(prescribed course of treatment or diet)
'soldiers don't finish' is the wordplay.
'soldiers' becomes 'regiment'.
'don't finish' means to remove the last letter.
'regiment' with its final letter removed is 'REGIMEN'.
(Other definitions for regimen that I've seen before include "Method of working" , "prescribed treatment" , "Prescribed system of diet and exercise - mere gin (anag)" , "Disciplined system" , "Course of diet, therapy" .)