Log jam caused by troublemaker on donkey at the end of the avenue (7)
I believe the answer is:
impasse
'log jam' is the definition.
'impasse' can be an answer for 'jam' (thesaurus). I am not sure about the 'log' bit.
'troublemaker on donkey at the end of the avenue' is the wordplay.
'troublemaker' becomes 'imp' (little devil).
'on' means one lot of letters go next to another.
'donkey' becomes 'ass' (ass is a term for a donkey).
'at the end of' indicates one should take the final letters.
The final letter of 'avenue' is 'e'.
'imp'+'ass'+'e'='IMPASSE'
'caused by' acts as a link.
Can you help me to learn more?
(Other definitions for impasse that I've seen before include "Lack of movement" , "'Deadlock, stalemate (7)'" , "Situation in which no progress can be made" , "hopeless situation?" , "Stalemate situation" .)