Chap with boy going round one big house (7)
I believe the answer is:
mansion
'one big house' is the definition.
(I've seen this in another clue)
'chap with boy going round' is the wordplay.
I cannot quite understand how this works, but
'chap' could be 'si' and 'si' is present in the answer.
'boy' could be 'mano' and 'mano' is found in the leftover letters.
A single letter 'n' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for mansion that I've seen before include "Handsome house as for Lord Mayor" , "Imposing house" , "Opulent house" , "Huge imposing residence" , "Huge abode" .)