Course army unit won't complete (7)
I believe the answer is:
regimen
'course' is the definition.
(I've seen this before)
'army unit won't complete' is the wordplay.
I cannot really see how this works, but
'army' could be 're' (Royal Engineers army regiment) and 're' is located in the answer.
'unit' could be 'gi' (Gi is an example) and 'gi' is found in the answer.
The remaining letters 'men' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for regimen that I've seen before include "Mere gin for a course of treatment" , "Prescribed course of diet, exercise, etc" , "Method of working" , "discipline" , "Plan for e.g. diet" .)