Liberals seem upset by society's work on injustice (3,10)
I believe the answer is:
les miserables
'work on injustice' is the definition.
(novel by Victor Hugo)
'liberals seem upset by society's' is the wordplay.
'upset by' indicates anagramming the letters.
'society' becomes 's' (common abbreviation in names of organisations).
'liberals'+'seem'='liberalsseem'
'liberalsseem' with letters rearranged gives 'lesmiserable'.
'lesmiserable'+'s'='LES MISERABLES'
(Other definitions for les miserables that I've seen before include "show" , "Musical from Victor Hugo" , "Victor Hugo novel, Valjean its hero" , "Musical based on a Hugo novel" , "Well-known musical" .)