Complaints of US postal workers — no money upfront and empty threats (8)
I believe the answer is:
ailments
'complaints' is the definition.
('ailment' can be a synonym of 'complaint')
'workers no money upfront and empty threats' is the wordplay.
'workers' becomes 'men' (men can mean staff or employees).
'no money' becomes 'ail' (I am not sure about this - if you are sure you should believe this answer much more).
'upfront' says to put letters next to each other (some letters go in front of others).
'and' is a charade indicator (letters next to each other).
'empty' suggests removing the centre.
'threats' with its middle removed is 'ts'.
'men' put after 'ail' is 'ailmen'.
'ailmen'+'ts'='AILMENTS'
'of us postal' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ailments that I've seen before include "Diseases or disorders" , "Maladies of manliest sort" , "Nail stem produces illnesses" , "Minor illnesses" , "Illnesses, complaints" .)