Illness reportedly went quickly (4)
'went quickly' is the definition.
(the time flew by)
'illness reportedly' is the wordplay.
'illness' becomes 'flu' (flu is a kind of health problem).
'reportedly' shows a homophone (sound like).
'flu' sounds like 'FLEW'.
(Other definitions for flew that I've seen before include "Dashed" , "Fled" , "Travelled by air" , "Shot" , "Rushed (by air?)" .)
'illness' is the definition.
(flu is a kind of health problem)
'reportedly went quickly' is the wordplay.
'reportedly' shows a homophone (sound like).
'went quickly' becomes 'flew' (the time flew by).
'flew' sounds like 'FLU'.
(Other definitions for flu that I've seen before include "Viral infection (abbr)" , "Infection reduced" , "Influenza, in short" , "Swine --; gastric --" , "Common ailment" .)