Three to get.
23A Aspiration of folk in Gateshead, say, to be quite modern (6) N???S?
25A Poet of the year appearing in catalogue (6) L???S?
21D Put down a cow as it were? (5) L????
23A NEWISH - NE (Gateshead) + wish (aspiration)
25A LYRIST - yr (year) inside list (catalogue)
21D LOWER - put down = lower; cattle low, therefore, they are lowers.