Answer: subtilize

AnswerCrossword Clue
subtilizeto introduce subtleties into or argue subtly about
subtilizeto make (the mind, senses, etc.) keen or discerning.
subtilizeto make subtle; now esp to argue subtly on
subtilizeto make (the mind, senses, etc.) keen or discerning; sharpen
subtilizeto elevate in character; sublimate
subtilizeto make subtle distinctions or to argue subtly