Being upset, stand it no more -- protest! (13)
I believe the answer is:
demonstration
'protest' is the definition.
(I've seen this before)
'being upset stand it no more' is the wordplay.
'being upset' indicates an anagram.
'stand'+'it'+'no'+'more'='standitnomore'
'standitnomore' anagrammed gives 'DEMONSTRATION'.
(Other definitions for demonstration that I've seen before include "It's to voice protest" , "Protest meeting" , "Protest march/meeting" , "Display showing how something works" , "March; proof" .)