Cite me, over such a nauseant (6)
I believe the answer is:
emetic
'a nauseant' is the definition.
('emetic' can be a synonym of 'nauseant')
'cite me over' is the wordplay.
'over' says the letters should be written in reverse.
'cite'+'me'='citeme'
'citeme' written backwards gives 'EMETIC'.
'such' is the link.
(Other definitions for emetic that I've seen before include "Cite me as containing sick-making substance" , "inducing sickness" , "Ipecacuanha is one" , "it will make one sick" , "Medicine designed to make one vomit" .)