Building worker dividing house (4-2)
I believe the answer is:
lean-to
'building' is the definition.
(I've seen this before)
'worker dividing house' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'dividing' indicates putting letters inside (inserted letters divide the word).
'house' becomes 'Leo' (Leo is an astrological house in the zodiac).
'ant' put inside 'leo' is 'LEAN-TO'.
(Other definitions for lean-to that I've seen before include "Penthouse" , "Hut" , "greenhouse, perhaps" , "Attached outbuilding" , "Building built against another" .)