Bears down on printing houses (7)
I believe the answer is:
presses
I believe this is a double definition.
'bears down on' is the first definition.
(to bear down on is to press on)
'printing houses' is the second definition.
(printing presses)
(Other definitions for presses that I've seen before include "Irons" , "Machines for printing" , "Machines to extract, eg, olive oil" , "Pushes" .)