Homes in which walls of blackwood are swapped for bricks (6)
I believe the answer is:
adobes
'for bricks' is the definition.
(adobe is a kind of brick)
'homes in which walls of blackwood' is the wordplay.
'homes' becomes 'ados' (I can't justify this - if you can you should give a lot more credence to this answer).
'in which' means one lot of letters goes inside another.
'walls of' means to remove the middle letters (only the edge letters remain).
'blackwood' becomes 'bloodwood tree' (bloodwood tree is a kind of blackwood).
'bloodwoodtree' with its middle taken out is 'be'.
'ados' enclosing 'be' is 'ADOBES'.
'are swapped' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for adobes that I've seen before include "Sun-dried building bricks" , "So a bed can turn up in houses of mud-brick" .)