1: Getting old drink in silver container (5)
3: Ball tops over-ripe bananas (3)
5: Bounder beheaded by slippery swimmer (3)
7: Proficient in arithmetic, starting with short division (5)
8: Prig had ma conceal midriff (9)
10: Deer I mistook for duck (5)
11: In fear of wheat head (3)
12: 4-down Arias hit high note in some of the lungs (3,3)