Not feeling good at a discount (5,3)
I believe the answer is:
below par
I believe this clue is a double definition.
'not feeling good' is the first definition.
(below par can mean unwell)
'at a discount' is the second definition.
(thesaurus)
(Other definitions for below par that I've seen before include "Worse than usual" , "Not in full health" , "Out of sorts" , "Lower than the average, as in golf score ( 5, 3)" , "Worse than expected" .)