Small body of soldiers also included in scheme (7)
I believe the answer is:
platoon
'small body 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' means one lot of letters goes inside another.
'scheme' becomes 'plan' (I've seen this before).
'too' going inside 'plan' is 'PLATOON'.
(Other definitions for platoon that I've seen before include "Sub-unit of a military company" , "Small body of soldiers" , "Subdivision of a company" , "Military group" , "Group under lieutenant" .)