Cloak policeman keeps on in front of house (6)
I believe the answer is:
poncho
'cloak' is the definition.
(I know that Poncho is a type of cloak)
'policeman keeps on in front of house' is the wordplay.
'policeman' becomes 'pc' (police constable).
'keeps' means one lot of letters goes inside another.
'in front of' says to put letters next to each other.
'house' becomes 'ho' (abbreviation for house).
'pc' enclosing 'on' is 'ponc'.
'ponc'+'ho'='PONCHO'
(Other definitions for poncho that I've seen before include "Garment with opening for head" , "A blanket-like cloak with a hole in the centre for the head" , "apparel" , "Overgarment with hole for head" , "South American cape" .)