Building material reductions lifted by business (6)
I believe the answer is:
stucco
'building material' is the definition.
(I've seen this in another clue)
'reductions lifted by business' is the wordplay.
'reductions' becomes 'cuts' (cut is a kind of reduction).
'lifted' says the letters should be written backwards (going up in down clue).
'by' means one lot of letters go next to another.
'business' becomes 'co' (short for company).
'cuts' written backwards gives 'stuc'.
'stuc'+'co'='STUCCO'
(Other definitions for stucco that I've seen before include "Plaster used for decorative moulding" , "Kind of plaster used for wall decoration" , "Fine plaster for ornamenting walls etc" , "Fine plaster for decoration" , "Plaster used for moulding decorations on walls or ceilings" .)