Adverse (8)
(Other definitions for untoward that I've seen before include "Inconvenient, unfortunate" , "vexing" , "Unfortunate or adverse" , "Unexpected and inconvenient" , "Unexpected, adverse" .)
'adverse' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for negative that I've seen before include "Gloom-ridden" , "Film showing black and white tones reversed" , "Expressing refusal, denial or disagreement" , "The photographic film expresses refusal" , "Pessimistic, discouraging" .)
'adverse' is the definition.
(thesaurus)
This is all the clue.
(Another definition for unpropitious that I've seen is " Boding ill".)