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