The term 'challenging one' can be summarized by the crossword solution 'darer'. A darer is someone who is willing to take risks and face difficult tasks. They are often seen as brave and courageous, as they are not afraid to take on a challenge. Darers are usually people who are not afraid to take risks and push themselves to their limits. They are often seen as inspiring and motivating, as they show others that it is possible to overcome obstacles and achieve success.