Qualm; uncertainty (5)
I believe the answer is:
doubt
I believe this is a double definition.
'qualm' is the first definition.
(thesaurus)
'uncertainty' is the second definition.
(I know that uncertainty can be written as doubt)
(Other definitions for doubt that I've seen before include "Suspicion" , "Uncertainty about the truth" , "Suspect" , "Distrust" , "Misgiving" .)