One put in additional clauses for commandos (7)
I believe the answer is:
raiders
'for commandos' is the definition.
(I've seen this in another clue)
'one put in additional clauses' is the wordplay.
'one put' is an insertion indicator.
'in additional' becomes 'a' (I can't explain this - if you can you should believe this answer much more).
'clauses' becomes 'riders' (rider is a kind of clause).
'a' put within 'riders' is 'RAIDERS'.
Can you help me to learn more?
(Other definitions for raiders that I've seen before include "Marauders" , "Attacking force" , "Marauding attackers" , "' - - of the Lost Ark'" .)