Feeling nauseous (6)
I believe the answer is:
queasy
'feeling nauseous' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for queasy that I've seen before include "Feeling slightly sick, maybe with indigestion" , "Feeling slightly sick, maybe at sea" , "Sickish" , "Squeamish - nauseous" , "One released from marriage" .)