In that case the arbiter or umpire finally gives the answer (9)
I believe the answer is:
therefore
'in that case' is the definition.
(thesaurus)
'the arbiter or umpire finally gives the answer' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'arbiter' could be 'ref' (I've seen this in another clue) and 'ref' is found within the answer.
'or' is present in the answer.
The remaining letters 'hee' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for therefore that I've seen before include "It follows" , "has a triangular formation in maths?" , "as result" , "In consequence" , "Consequently - for that reason" .)