Residents suffering fatigue (9)
I believe the answer is:
tiredness
'fatigue' is the definition.
(synonyms)
'residents suffering' is the wordplay.
'suffering' is an anagram indicator.
'residents' with letters rearranged 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" .)