Frail men talking about complaint (7)
I believe the answer is:
ailment
'complaint' is the definition.
('ailment' can be a synonym of 'complaint')
'frail men talking about' is the wordplay.
'about' indicates a hidden word.
'AILMENT' is hidden in the letters of 'frail men talking'.
(Other definitions for ailment that I've seen before include "infirmity" , "Tummy upset, for instance" , "Slight but persistent illness" , "I lament (anag.)" , "Minor illness" .)