Squad also included in scheme (7)
I believe the answer is:
platoon
'squad' is the definition.
(I know that platoon is a type of squad)
'also included in scheme' is the wordplay.
'also' becomes 'too' (synonyms).
'included in' means one lot of letters goes inside another.
'scheme' becomes 'plan' (synonyms).
'too' going into 'plan' is 'PLATOON'.
(Other definitions for platoon that I've seen before include "Small body of soldiers" , "detail" , "Military group" , "Infantry unit" , "Military squad" .)