Email mentioned housing complaint (7)
I believe the answer is:
ailment
'complaint' is the definition.
('ailment' can be a synonym of 'complaint')
'email mentioned housing' is the wordplay.
'housing' indicates a hidden word (part of the clue houses the answer).
'AILMENT' can be found hidden inside 'email mentioned'.
(Other definitions for ailment that I've seen before include "Minor illness" , "Malady" , "problem" , "infirmity" , "Sickness" .)