A slip crossing over large ditch (7)
I believe the answer is:
abolish
'ditch' is the definition.
(I've seen this before)
'a slip crossing over large' is the wordplay.
'slip' becomes 'bish' (bish can mean an error).
'crossing' indicates putting letters inside (to cross can mean to go over or around).
'over large' becomes 'ol' (this could be a standard abbreviation which I don't know about).
'bish' placed around 'ol' is 'bolish'.
'a'+'bolish'='ABOLISH'
Can you help me to learn more?
(Other definitions for abolish that I've seen before include "Stop or put an end to" , "delete" , "Put an end to, as with slavery" , "Cancel, annul" , "Quash" .)