As a result, player goes after umpire intervening in unfinished argument (9)
I believe the answer is:
therefore
'as a result' is the definition.
(I've seen this before)
'player goes after umpire intervening in unfinished argument' is the wordplay.
I cannot really understand how this works, but
'umpire' could be 'ref' (I've seen this before) and 'ref' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for therefore that I've seen before include "has a triangular formation in maths?" , "Consequently - for that reason" , "Ergo" , "It follows" , "as result" .)