1: Sounds like a bright child (3).
2: Concealed hot part of psyche (3)
3: Explorer taking stuff back and beginning to observe game (5,4)
4: Dispatches last bits following Saturday (5)
5: Flower, large one, set up outside (5)
8: Introduction to book by mere poet (5)
9: Stories least translated (5)
12: 4-down Arias hit high note in some of the lungs (3,3)
13: Frost to cover the cake (3)