Seal upper part of single-storey residence (4)
I believe the answer is:
bung
'seal' is the definition.
(bung can mean a seal or stopper)
'upper part of single-storey residence' is the wordplay.
'upper part of' suggests halving the letters (the top half of the word).
'single-storey residence' becomes 'bungalow' (type of single-storey building).
'bungalow' cut in half is 'BUNG'.
(Other definitions for bung that I've seen before include "Bribe - bottle stopper" , "Drum; antelope" , "Tip, bribe (sl.)" , "Cask stopper" , "Bribe (slang)" .)