Uneven grating below par (5)
I believe the answer is:
rough
This clue is a triple definition!
'uneven' is the first definition.
(associated in meaning)
'grating' is the second definition.
(synonyms)
'below par' is the third definition.
(feeling below par can mean feeling rough or ill)
(Other definitions for rough that I've seen before include "Boisterous; uneven" , "Rowdy - part of golf course" , "scratchy" , "Not gentle; unrefined" , "Estimated" .)