5. sounds like your personal fright cry (3,5)
11. principaality's uncommon drill? (5,7)
13. divide a mountain chain (9)
16. red light for a sailor (4)
17. grumble (6)
23. to be eaten on 1st january 2012 (not haggis) (6)
27. 3.141593 after a fraud (6)
29. in to disturb other swimmers (6)
30. roman road in vehicle (6)
31. blanched enticement (9)