President's house knocked down (6)
I believe the answer is:
hoover
'president's' is the definition.
(I've seen this before)
'house knocked down' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'knocked down' becomes 'over' (I am not sure about this - if you are sure you should believe this answer much more).
'ho'+'over'='HOOVER'
Can you help me to learn more?
(Other definitions for hoover that I've seen before include "Clean with vacuum cleaner" , "J Edgar . . . . . . was FBI chief" , "J Edgar ...... was FBI boss." , "Type of 5 down" , "US president, 1929-33" .)