Loud appeal to the umpire brings uproar (6)
I believe the answer is:
outcry
'uproar' is the definition.
(I've seen this in another clue)
'loud appeal to the umpire' is the wordplay.
I cannot really understand how this works, but
'appeal' could be 'cry' (as in a cry for help) and 'cry' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
The remaining letters 'ou' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'brings' acts as a link.
Can you help me to learn more?
(Other definitions for outcry that I've seen before include "Exclamations of opposition" , "commotion" , "Vociferous protest" , "Public clamour" , "Public show of anger" .)