Have the flu, say (3)
I believe the answer is:
ail
'have the flu say' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ail that I've seen before include "Be the worse for wear" , "Cause to feel indisposed" , "distress" , "Sink" , "Trouble, afflict; be sickly" .)