Clown about cause of wharf failure (7)
I believe the answer is:
pierrot
'clown about cause' is the definition.
'pierrot' can be an answer for 'clown' (I've seen this before). I'm unsure of the 'about cause' bit.
'wharf failure' is the wordplay.
'wharf' becomes 'pier' (I've seen this in another clue).
'failure' becomes 'rot' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pier'+'rot'='PIERROT'
'of' is the link.
Can you help me to learn more?
(Other definitions for pierrot that I've seen before include "he's white-faced at work" , "Sad white-faced clown" , "French panto clown with whitened face" , "Period; incantation" , "I report on French pantomime clown" .)