1: Essay about one mathematical function in three volumes (7)

5: Chatter about some pay-back (3)

6: We turned up with endless Irish pitchers (5)

8: Town's rail transport, not express? (9)

9: Prom couple steals crown from teen dress up (5)

10: I shall be sick! (3)

12: Pair of witnesses' mostly smooth transfer may end with Tony Soprano, possibly (7)

1: Totally lacking a lofty plaything (3)

2: Mischievous child learning to beg (7)

3: Suggestions for obvious singles (9)

4: Moulding material to be included in upcoming miniseries (5)

7: It's exciting, for example, holding a tongue (7)

8: Flower part to lapse badly (5)

11: Non-clerical song (3)