Group of soldiers also included in scheme (7)
I believe the answer is:
platoon
'group of soldiers' is the definition.
(I've seen this before)
'also included in scheme' is the wordplay.
'also' becomes 'too' ('too' can be a synonym of 'also').
'included in' indicates putting letters inside.
'scheme' becomes 'plan' (I've seen this before).
'too' going into 'plan' is 'PLATOON'.
(Other definitions for platoon that I've seen before include "Division of company" , "Company's subdivision" , "Military group" , "Army unit" , "Group of soldiers" .)