Trip with commission (6)
I believe the answer is:
errand
I believe this clue is a double definition.
'trip' is the first definition.
(errand is a kind of trip)
'commission' is the second definition.
(thesaurus)
'with' acts as a link.
(Other definitions for errand that I've seen before include "run one" , "Short journey done for others" , "Short journey to carry message for Renard" , "short shopping trip" , "Native of a former German kingdom" .)