Express delight arising from outhouse having been cleaned (6)
I believe the answer is:
washed
'cleaned' is the definition.
(washing is a kind of cleaning)
'express delight arising from outhouse' is the wordplay.
'express delight' becomes 'aw' (I am not sure about this - if you are sure you should believe this answer much more).
'arising' shows that the letters should be reversed in order.
'from' is a charade indicator (letters next to each other).
'outhouse' becomes 'shed' (a shed is an outside building).
'aw' back-to-front is 'wa'.
'wa'+'shed'='WASHED'
'having been' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for washed that I've seen before include "free of sin" , "spotless?" , "Wall up; imprison" , "Cleaned with liquid" , "Used soap and water" .)