Residents suffering fatigue (9)
I believe the answer is:
tiredness
'fatigue' is the definition.
(I know that fatigue can be written as tiredness)
'residents suffering' is the wordplay.
'suffering' indicates an anagram.
'residents' anagrammed gives 'TIREDNESS'.
(Other definitions for tiredness that I've seen before include "Lassitude; residents (anag.)" , "Weary feeling" , "Residents in state of fatigue" , "7 (anag)" , "That's liable to occur at midnight" .)