What may decide winner of cup, about right after draw (10)
I believe the answer is:
tiebreaker
'what may decide winner' is the definition.
'cup about right after draw' is the wordplay.
'cup' becomes 'beaker' (beaker is a kind of cup).
'about' means one lot of letters goes inside another.
'right' becomes 'r' (common abbreviation).
'after' means one lot of letters go next to another.
'draw' becomes 'tie' ('tie' can be a synonym of 'draw'**).
'beaker' going around 'r' is 'breaker'.
'breaker' put after 'tie' is 'TIEBREAKER'.
'of' is the link.
(Other definitions for tiebreaker that I've seen before include "A means of separating equal winners" , "Game decider" , "It's decisive" , "settler" .)