Army units also included in schemes (8)
I believe the answer is:
platoons
'army units' is the definition.
(platoon is a kind of army unit)
'also included in schemes' is the wordplay.
'also' becomes 'too' (synonyms).
'included in' indicates putting letters inside.
'schemes' becomes 'plans' (I've seen this in another clue).
'too' going into 'plans' is 'PLATOONS'.
(Other definitions for platoons that I've seen before include "Army units" , "Military units" , "small bodies of soldiers" .)