"decisive hint" is correct and usable in written English.
You can use it when you want to indicate a clue or suggestion given that leads to a definite conclusion or decision. For example: The detective received a decisive hint from an anonymous source that helped him solve the case.
These quotations all suggest the idea that politics, or some significant area of it, such as international relations, falls quite outside the provenance of morality, thus denying morality comprehensiveness, though the reference to morality's failure to be "decisive" hints at a denial of dominance.
Finally, the soldiers heard scream(s) which hinted decisive blows, but it was unclear which of the two was successful.
The euro has been falling for weeks because of broad hints that decisive action would be taken to raise the eurozone's inflation rate from its worryingly low level of 0.1%.
Paleogenomic studies of reconstructing ancestral karyotypes may provide hints of decisive evolutionary steps in a lineage (Yegorov and Good 2012).
As for the body, Jason Rhoades evokes it with profane anatomical slang written in neon and an assemblage of dangling objects, beginning with a T-shirt, a work that provides only a hint of the decisive way in which Mr. Rhoades's work bridges the Nauman-McCarthy duality.
Whatever it might be, the rumored CDMS signal could be a hint of more decisive observations to come.
While not in itself a decisive shift for a city that remained besieged, the swift advance, made with few rebel casualties, carried both signs of rebel optimism and hints of the weakness of at least one frontline loyalist unit.
There's a hint of Mrs. Dalloway about her (her most decisive act is to go out to buy flowers), and even in company she seems cocooned in her own thoughts.
The decisive free program on Saturday will provide better evidence, but there was certainly a hint of the end of a reign on Friday.
This hints that the adsorption geometry of single molecules seems to be decisive for the organic crystal nucleation as expected by the growth model.
Yet, as in most other times when the world seems to be about to be plunged in darkness, there emerges a glimmer of hope, a hint of the emergence of a set of circumstances that hints at the possibility of decisive action.
