Here are the possible solutions for one still maturing clue
Answer
Clue
Relevancy
teen
Clue
One still maturing
tbill
Clue
One maturing quickly, for short
sufjanstevens
Clue
Singer-songwriter who announced after his album "Michigan" that he would do one for every state...still...still...workin' on that one. Two down, 48 to go!