Have advantage over United in goalless game? (5)
I believe the answer is:
outdo
'have advantage over' is the definition.
'united in goalless game?' is the wordplay.
'united' becomes 'utd' (common abbreviation as in names of sports teams).
'in' indicates putting letters inside.
'goalless game?' becomes 'oo' (resembles 0-0 score).
'utd' placed into 'oo' is 'OUTDO'.
(Other definitions for outdo that I've seen before include "Perform better than (someone)" , "Eclipse" , "Exceed" , "going to top?" , "Surpass, go one better than" .)