Vagrant bowled over by house (4)
I believe the answer is:
hobo
'vagrant' is the definition.
(I know that hobo is a type of vagrant)
'bowled over by house' is the wordplay.
'bowled' becomes 'b' (cricket abbreviation).
'over' becomes 'o' (cricket abbreviation).
'by' is a charade indicator (letters next to each other).
'house' becomes 'ho' (abbreviation for house).
'b'+'o'='bo'
'bo' put after 'ho' is 'HOBO'.
(Other definitions for hobo that I've seen before include "Deer, situated at the back" , "American tramp" , "Bum" , "Vagrant, tramp" , "Vagrant (American)" .)