I said I saw a most unpleasant scene (7)
I believe the answer is:
eyesore
'i said i' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'saw a most unpleasant scene' is the wordplay.
'saw' becomes 'eyed' (I've seen this before).
'a most' means to remove the last letter.
'unpleasant scene' becomes 'sore' (I can't justify this - if you can you should give a lot more credence to this answer).
'eyed' with its final letter taken away is 'eye'.
'eye'+'sore'='EYESORE'
Can you help me to learn more?
(Other definitions for eyesore that I've seen before include "Unpleasant sight" , "Something exceedingly ugly" , "Hideous building" , "bad sight" , "Hideous sight" .)