Perhaps Tory U-turn after mistake is an accident waiting to happen (5,4)
I believe the answer is:
booby trap
'mistake is an accident waiting to happen' is the definition.
I can't judge whether this definition defines the answer.
'perhaps tory u-turn after' is the wordplay.
'perhaps' becomes 'boob' (I can't explain this - if you can you should give a lot more credence to this answer).
'tory' becomes 'party' (the Conservative or Tory Party is an example).
'u-turn' says the letters should be written backwards.
'after' is a charade indicator (letters next to each other).
'party' written backwards gives 'ytrap'.
'boob'+'ytrap'='BOOBY-TRAP'
Can you help me to learn more?
(Other definitions for booby trap that I've seen before include "Unexpected explosive device" , "Bra, maybe" , "Hidden weapon" , "Hazard for the unwary" , "Device for practical joke" .)