Do some maintenance on top of the large mansion, one hears (8)
I believe the answer is:
overhaul
'do some maintenance' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'on top of the large mansion one hears' is the wordplay.
'on top' indicates taking the first letters.
'the large' becomes 'ver' (I am not sure about this - if you are sure you should believe this answer much more).
'mansion' becomes 'hall' (synonyms).
'one hears' shows a homophone (sound like) (I've seen 'hear' mean this).
The first letter of 'of' is 'o'.
'hall' is a homophone of 'haul'.
'o'+'ver'+'haul'='OVERHAUL'
Can you help me to learn more?
(Other definitions for overhaul that I've seen before include "Repair fully and renew" , "Examine and repair (machinery)" , "Test and repair - pass" , "Check-up" , "Recondition" .)