Complaint that may be socially acceptable in time (4)
I believe the answer is:
ague
'complaint' is the definition.
(ague is a kind of disease)
'socially acceptable in time' is the wordplay.
'socially acceptable' becomes 'u'.
'in' is an insertion indicator.
'time' becomes 'age' (age is a kind of time).
'u' put within 'age' is 'AGUE'.
'that may be' acts as a link.
(Other definitions for ague that I've seen before include "Sickness" , "Feverish fit" , "met with cheek in Twelfth Night" , "Hot and cold fever" , "Fit of the shakes" .)