Queasiness (6)
I believe the answer is:
nausea
'queasiness' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nausea that I've seen before include "Feeling of revulsion" , "Sickness, biliousness" , "Condition of feeling imminent sickness" , "A feeling of disgust or illness" , "Feeling of sickness or disgust" .)