According to report virus was airborne (4)
I believe the answer is:
flew
'was airborne' is the definition.
(flew in the air)
'according to report virus' is the wordplay.
'according to report' shows a homophone (sound like).
'virus' becomes 'flu'.
'flu' is a homophone of 'FLEW'.
(Other definitions for flew that I've seen before include "Rushed (by air?)" , "Went quickly" , "Dashed" , "lip" , "Travelled by plane" .)