Commander about to complete programme (6)
I believe the answer is:
agenda
'programme' is the definition.
(agenda is a kind of programme)
'commander about to complete' is the wordplay.
'commander' becomes 'aga' (I've seen this before).
'about' indicates putting letters inside.
'to complete' becomes 'end' (I've seen this before).
'aga' placed around 'end' is 'AGENDA'.
(Other definitions for agenda that I've seen before include "plan of things to be done" , "List of items to be done" , "things to discuss" , "Topic list for meeting" , "Topics for a meeting" .)