Answer: flintier

AnswerCrossword Clue
FLINTIERHarder.
FLINTIERMore obdurate
flintierFLINTY, resembling flint
flintiercomposed of, containing, or resembling flint, esp. in hardness
flintierresembling flint
flintierern unyielding flinty determination
flintierunyielding; unmerciful; obdurate