Commander describes complete plan (6)
I believe the answer is:
agenda
'plan' is the definition.
(agenda is a kind of plan)
'commander describes complete' is the wordplay.
'commander' becomes 'aga' (I've seen this before).
'describes' is an insertion indicator (describe can mean to form the outline of).
'complete' becomes 'end' (I've seen this before).
'aga' placed around 'end' is 'AGENDA'.
(Other definitions for agenda that I've seen before include "Meeting's topics" , "Something perhaps hidden" , "List of items of business for committee" , "List of matters to be discussed at a meeting" , "List of items for discussion at a meeting" .)