Beat walls in vacated residence having sideboards (9)

'having sideboards' is the definition.
I can't judge whether this defines the answer.

'beat walls in vacated residence' is the wordplay.
'beat' becomes 'whisked' (I can't justify this - if you can you should believe this answer much more).
'walls in' means one lot of letters goes inside another (inserted letters are walled in).
'vacated' means to remove the middle letters (internal letters vacate the word).
'residence' with its middle removed is 're'.
'whisked' placed around 're' is 'WHISKERED'.

Can you help me to learn more?