Inhabitant of the White House is a sucker (6)
I believe the answer is:
hoover
I believe this clue is a double definition.
'inhabitant of the white house' is the first definition.
(Herbert Hoover)
'sucker' is the second definition.
(a vacuum cleaner, which sucks)
'is a' is the link.
(Other definitions for hoover that I've seen before include "Vacuum cleaner of the old American president" , "Former president of US and vacuum cleaner" , "US president in House throughout" , "US president, 1929-33" , "J Edgar . . . . . . was FBI chief" .)