Knocks down several storeys? (6)
I believe the answer is:
floors
This might be a double definition.
'knocks down' is the first definition.
('floor' can be a synonym of 'knock down')
'several storeys?' is the second definition.
'floors' can be an answer for 'storeys?' ('floor' can be a synonym of 'storey'). I'm not sure about the 'several' bit.
Can you help me to learn more?
(Other definitions for floors that I've seen before include "Knocks down with a punch" , "Tiers in a building" , "Stumps (with question)" , "Inside horizontal surfaces" , "Knocks person down in a fight or confounds" .)