Perpetually angry people irritating to barmen (4-1-3)
I believe the answer is:
rent-a-mob
'perpetually angry people' is the definition.
(rent-a-mob means a constantly protesting group)
'irritating to barmen' is the wordplay.
'irritating' indicates anagramming the letters (letters irritated or excited).
'to'+'barmen'='tobarmen'
'tobarmen' is an anagram of 'RENT-A-MOB'.
(Other definitions for rent-a-mob that I've seen before include "mass of people" , "Hired crowd (facet.)" , "Crowd for hire" .)