1: Argue about something boring (5)

4: Fathers start to applaud, in afterthought (3)

6: Article proscribes old Greeks (7)

7: Decision tree's unusual goal: mirth? (9)

9: Pitman's state goddess (7)

11: Picture a dessert without topping (3)

12: Rod set up sweetheart to run away together (5)

1: Drawing, for example, a bit of a cartoon (3)

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

3: Change order: Raise scope (9)

4: Infection leads from partly uncooked steak (3)

5: Father's into whips and chains, a violent action (5)

7: Run around near a stadium (5)

8: Trunk and tangled roots (5)

9: Ran into a section of the time-table (3)

10: Number One in facetiousness (3)