Complaint or grievance (5)
I believe the answer is:
gripe
This clue is a double definition.
'complaint' is the first definition.
(an objection or source of annoyance)
'grievance' is the second definition.
(I've seen this before)
(Other definitions for gripe that I've seen before include "beef" , "Complain, grouse" , "Grumble informally" , "Complain; stomach pain" , "Keep on complaining" .)