Gained an advantage, committed to staff (6)
I believe the answer is:
scored
I believe this is a double definition.
'gained an advantage' is the first definition.
'committed to staff' is the second definition.
(as in committing musical notes to a staff or stave)
(Other definitions for scored that I've seen before include "ran" , "Put the ball in the net, or scratched" , "Cut" , "graded" , "Wrote 8 -- made marks on the surface" .)