1: Oxygen is pretty amusing. (3)

3: Scheme conclusion for jet set (5)

5: Void three stones (5)

6: Direct object (3)

7: Measuring unusual flowers (9)

9: Nightwear and jersey top added in afterthought (3)

10: A period set around one Dostoyevsky character (5)

11: Supplementing oriental ruler (5)

12: First get a French weapon. (3)

1: Good Republican source of life-giving system for short-handed office workers (5)

2: Hesper's fresh fields (7)

3: Bringing up the kids - Dad's paying for it (9)

4: Thumb Drum? (3)

6: Diverting a dupe with wrong input (7)

8: Posed in glossy fabric (5)

9: He wrote a bit of poetry! (3)