Successfully jump over high bunk (5,3)
I believe the answer is:
clear off
'successfully jump over high bunk' is the definition.
I can't judge whether this definition defines the answer.
'over high bunk' is the wordplay.
'over' says to put letters next to each other (in a down clue, some letters go over others).
'high' becomes 'off' (both can refer to rotten food).
'bunk' becomes 'clear' (I can't explain this - if you can you should give a lot more credence to this answer).
'off' after 'clear' is 'CLEAR OFF'.
Can you help me to learn more?
(Other definitions for clear off that I've seen before include "Go away - transparently" , "Begone (colloq.)" , "Leave" , "Get lost!" , "Skedaddle" .)