Show preference for a simple building (4-2)
I believe the answer is:
lean-to
'a simple building' is the definition.
(I've seen this before)
'show preference for' is the wordplay.
'show preference' becomes 'lean' (I've seen this in another clue).
'for' becomes 'to' (eg both can mean 'in the opinion of').
'lean'+'to'='LEAN-TO'
(Other definitions for lean-to that I've seen before include "Building supported by another" , "Outhouse" , "Attached outbuilding" , "Building with roof resting against larger building (4, 2)" , "Outbuilding propped against another wall" .)